MEMCAL 


Gift  of 


G.H.    Evans,    M.D. 


ANATOMY  AND  PHYSIOLOGY 

FOR  TRAINING  SCHOOLS  AND  OTHER 
EDUCATIONAL  INSTITUTIONS 

BUNDY 


TEXT-BOOK 

OF 

ANATOMY  AND  PHYSIOLOGY 

FOR  TRAINING  SCHOOLS  AND  OTHER 
EDUCATIONAL  INSTITUTIONS 


BY 

ELIZABETH  R.  BUNDY,  M.  D. 

MEMBER   OF   THE  MEDICAL  STAFF   OF   THE  WOMAN'S  HOSPITAL  OF  PHILADELPHIA;  GYNECOLOGIST 

NEW   JERSEY  TRAINING  SCHOOL,  VINELAND;  FORMERLY    ADJUNCT   PROFESSOR  OF 

ANATOMY,  AND  DEMONSTRATOR  OF  ANATOMY  IN  THE   WOMAN'S    MEDICAL 

COLLEGE    OF    PENNSYLVANIA;    FORMERLY    SUPERINTENDENT 

OF  CONNECTICUT  TRAINING  SCHOOL  FOR  NURSES 

NEW  HAVEN,   ETC. 


FOURTH  EDITION 
REVISED  AND  ENLARGED 


WITH  A  GLOSSARY  AND  243  ILLUSTRATIONS 
46    OF    WHICH,  ARE  .PRIJNT^D    I,N.  COLORS 


PHILADELPHIA 

P.   BLAKISTON'S   SON   &   CO 

1012  WALNUT   STREET 


COPYRIGHT,  1906,  BY  P.  BLAKISTON'S  SON  &  Co. 

PRINTED,  1906. 
REPRINTED,  1907,  1909,  1910,  1911. 

SECOND  EDITION. 
COPYRIGHT,  1912,  BY  P.  BLAKISTON'S  SON  &  Co. 

PRINTED,  1912. 

REPRINTED  WITH  CORRECTIONS,  1913. 
REPRINTED  SEPTEMBER,  1913. 

THIRD  EDITION. 
COPYRIGHT,  1914,  BY  P.  BLAKISTON'S  SON  &  Co. 

PRINTED,  1914. 
REPRINTED  WITH  CORRECTIONS,  OCTOBER,  1914. 

REPRINTED. 
FOURTH  EDITION. 

COPYRIGHT,  1916,  BY  P.  BLAKISTON'S  SON  &  Co. 
PRINTED,  1916. 


THE.  MAPLE-  PRESS. .YORK.  PA 


PREFACE  TO  THE  FOURTH  EDITION 


The  fourth  edition  of  this  book,  like  the  two  preceding  ones, 
has  been  prepared  with  the  hope  that  by  certain  changes  and  addi- 
tions, it  will  meet  the  still  increasing  demand  for  a  text-book  which 
shall  present  the  subject  of  Physiology  as  well  as  Anatomy,  in  a 
manner  both  practical  and  available  to  the  student. 

To  include  these  two  large  subjects  under  one  cover,  with  the 
necessary  brevity  and  still  with  sufficient  clearness,  is  a  task  with 
difficulties  of  its  own,  but  it  is  undertaken  with  the  earnest  endeavor 
to  meet  the  demand  created  by  present  requirements  as  well  as 
may  be  with  the  inevitable  problem  of  selection  or  omission, 
which,  however  carefully  considered,  must  remain  a  matter  of 
judgment  and  experience. 

The  plan  has  been  adopted  in  the  descriptions — to  emphasize 
those  characteristics  which  are  most  essential  and  which  may  be 
most  readily  grasped  and,  by  reason  of  practical  application, 
remembered. 

The  original  purpose  of  the  author — to  provide  a  special  text- 
book of  Anatomy — still  remains  in  effect,  since  only  by  means  of 
a  knowledge  of  structure  and  form  can  an  understanding  of  use 
or  function  be  reached. 

The  student  is  referred  to  the  Glossary  for  the  meaning  of 
unfamiliar  terms,  and  to  the  lines  of  smaller  type  for  various  par- 
ticulars which  may  be  found  useful  as  experience  indicates  the 
need  for  reference. 

The  original  illustrations  drawn  for  this  book  are  all  retained 
and  several  new  ones  from  other  sources  are  added. 

Again  the  author  desires  to  express  appreciation  of  suggestions 
and  kind  words  from  officials  of  schools  where  the  book  is  in  use. 

PHILADELPHIA  ELIZABETH  R.  BUNDY. 

3;iU'J 


PREFACE  AND  DEDICATION  TO  FIRST  EDITION 


The  pupil-nurse  in  a  training-school  has  very  few  hours  at  com- 
mand for  the  study  of  text-books,  but  it  is  hoped  that  she  may 
find  in  this  "Anatomy  for  Nurses"  an  aid  to  the  acquirement  of 
that  knowledge  of  the  human  body  which  is  essential  to  the  full 
understanding  of  her  important  duties. 

In  preparing  a  book  of  this  kind,  the  inevitable  difficulty  of 
selection,  when  dealing  with  a  subject  of  such  magnitude,  is  at  once 
manifest.  What  appears  from  one  point  of  view  to  be  of  minor 
interest,  is  from  another  paramount  in  importance;  while  in  truth, 
no  detail  is  of  itself  insignificant. 

The  author  trusts  that  in  the  present  work  such  matters  as  are 
not  available  for  immediate  use  in  the  hospital  ward  may  still  be  of 
value,  to  meet  the  growing  need  of  the  graduate-nurse  as  she  finds 
herself  developing  with  the  practice  of  her  profession.  It  was,  in 
part,  to  meet  this  frequently  expressed  need  that  the  work  was 

undertaken. 

********* 

Concerning  the  use  of  anatomic  terms,  indications  point  to  the 
general  adoption  of  the  nomenclature  accepted  by  the  German 
Anatomical  Society  at  the  meeting  of  1895,  in  Basle,  Switzerland. 
The  B.  N.  A.,  as  it  is  called,  will  soon  be  in  use  among  the  younger 
physicians  at  least;  therefore,  many  of  the  terms  belonging  to  it  are 
here  introduced,  and  several  tables  are  given  which  include  names 
not  found  in  the  text. 

The  author  gratefully  acknowledges  her  indebtedness  to  Dr. 
Marie  L.  Bauer  for  valuable  aid  in  the  preparation  of  the  book, 
and  to  Drs.  Frances  C.  Van  Gasken  and  J.  William  McConnell 
for  assistance  in  the  reading  of  proofs  and  for  helpful  suggestions. 

The  original  illustrations,  most  of  which  are  printed  in  colors, 
arerdrawn  by  Chas.  F.  Bauer. 

To  the  members  of  the  nursing  profession,  with  cherished  recol- 
lections of  labors  and  responsibilities  shared,  this  Text-book  of 
Anatomy  is  dedicated. 

ELIZABETH  R.  BUNDY. 
vii 


CONTENTS 


INTRODUCTORY 

PAGE 

Plan  of  study;  anatomic  terms;  muscle,  nerve,  and  connective  tissues;  epithelial 
tissues;  gland  structure;  serous  and  mucous  membranes;  processes  included 
in  metabolism  of  the  body;  chemical  elements  and  symbols i 

CHAPTER  I 
BONE  TISSUE  AND  BONE  CLASSIFICATION.    ARTICULATIONS 

Chemical  composition  of  bone;  structure  of  osseous  tissue;  marrow;  medullary 
and  nutrient  canals;  shapes  and  surfaces;  periosteum;  ossification;  divisions 
of  the  skeleton;  joint  movements;  reward n 

CHAPTER  II 
BONES  AND  ARTICULATIONS  OF  THE  SKULL 

Bones  of  the  cranium;  sutures  and  fontanelles;  bones  of  the  face;  the  mandibular 
joint;  the  skull  as  a  whole;  four  larger  fossae  of  the  skull;  the  teeth;  dentition; 
care  of  the  teeth;  clinical  and  obstetric  notes 20 

CHAPTER  III 
BONES  AND  ARTICULATIONS  OF  THE  SPINAL  COLUMN  AND  TRUNK 

The  vertebrae;  ligamenta  flava;  ligamentum  nuchce;  movements  of  spinal  column; 
spinal  curves;  bones  and  articulations  of  the  thorax;  the  pelvic  girdle;  sacro- 
sciatic  ligaments;  dorsal  and  ventral,  or  neural  and  visceral  cavities;  clinical 
and  obstetric  notes 39 

CHAPTER  IV 
BONES  AND  ARTICULATIONS  OF  THE  EXTREMITIES 

Bones  of  the  upper  extremity;  pronation  and  supination;  bones  of  the  lower 
extremity;  patella;  Y -ligament,  crucial  ligaments;  arches  of  the  foot;  com- 
parison of  extremities;  articular  nerves;  clinical  and  surgical  notes;  special 
notes 54 

CHAPTER  V 
COMPLETION,  REPAIR  AND  PHYSIOLOGY  OF  BONES 

Completion  of  long  bones;  the  skeleton  at  different  ages;  bones  in  infancy;  green- 
stick  fracture;  rachitis;  spina  bifida;  process  of  repair;  physiology  of  bone 
tissues;  surgical  and  special  notes '. 75 

ix 


X  CONTENTS 

CHAPTER  VI 

THE    CONNECTIVE    TISSUE    FRAMEWORK    AND    SKELETAL    MUSCLE 

SYSTEM 

Fascia,  deep  and  superficial;  inguinal  ligament;  bursae;  structure  of  muscles; 
tendon  and  aponeurosis;  origin  and  insertion;  muscles  of  expression,  of  neck 
and  thorax;  abdominal  muscles  and  linea  alba;  sheath  of  rectus,  semilunar 
and  transverse  lines.  Diaphragm;  surgical  and  clinical  notes;  special  points .  80 

CHAPTER  VII 
MUSCLES  OF  THE  EXTREMITIES 

Structure  and  action  of  muscles  of  upper  extremity;  axillary  space;  pronators  and 
supinators;  vaginal  synovial  membranes;  annular  ligaments;  palmar  fascia; 
muscles  of  lower  extremity;  popliteal  space;  annular  ligaments;  physiology 
of  muscle  tissue;  muscle  tissue  a  source  of  heat  and  electricity;  tetanus; 
cramp;  fatigue;  clinical  notes;  special  points;  classification  by  action.  .  .  .  101 

CHAPTER  VIII 
THE  ORGANS  OF  DIGESTION 

Alimentary  tract  or  canal;  glands  of  digestive  apparatus;  enzymes;  saliva,  alka- 
line; the  stomach;  gastric  juice,  acid;  the  intestine;  intestinal  fluids,  alkaline; 
villi;  ileo-colic  valve;  cecum  and  appendix;  rectum  and  anal  sphincters; 
peristalsis;  liver  and  gall  bladder;  bile;  the  porta;  notes,  clinical  and  surgical .  130 

CHAPTER  IX 
PHYSIOLOGY  OF  THE  DIGESTIVE  ORGANS.    FOOD.     ABSORPTION 

Four  classes  of  foods  in  dietary;  air  as  food;  food  combination;  reasons  for  cook- 
ing food;  digestion,  mechanical  and  chemical;  mastication,  insalivation; 
gastric  digestion  (acid),  chyme;  intestinal  digestion  chyle;  peristalsis;  absorp- 
tion; clinical  notes 153 

CHAPTER  X 
THE  BLOOD  AND  CIRCULATORY  ORGANS 

Blood-corpuscles  or  cells.  Erythrocytes  and  leucocytes;  ameboid  movements, 
diapedesis;  plasma  (alkaline);  normal  saline  solution;  arteries,  capillaries, 
veins^bhe  heart;  chambers  and  valves  of  heart;  endocardium;  systole  and 
diastole;  the  pulse;  pericardium;  course  of  blood  through  the  heart;  innerva- 
tion  of  the  heart;  surgical  an d  clinical  notes;  important  notes 171 

CHAPTER  XI 
THE  CIRCULATION  OF  THE  BLOOD 

Pulmonary  vessels;  aorta  and  branches;  arteries  of  the  head,  of  the  upper  ex- 
tremity; palmar  arches;  thoracic,  abdominal  and  pelvic  arteries;  arteries  of 
the  lower  extremity;  veins,  deep  and  superficial;  jugular  veins;  azygos  veins; 
superior  vena  cava;  inferior  vena  cava;  portal  circulation;  fetal  circulation; 
collateral  circulation;  clinical  and  surgical  notes 187 


CONTENTS  XI 

CHAPTER  XII 
PHYSIOLOGY  OF  THE  BLOOD 

Important  functions  of  the  blood;  coagulation;  formation  of  fibrin;  coagulation- 
time;  phagocytosis;  opsonins  and  opsonic  index;  antibodies;  hypodermo- 
clysis;  transfusion;  osmosis;  blood  pressure;  hemorrhage  and  control  of  hem- 
orrhages; clinical  notes',  important  notes 213 

CHAPTER  XIII 
THE  LYMPH  SYSTEM 

Lymph  spaces,  capillaries,  and  vessels;  lymph,  origin;  lymph  glands  or  nodes; 
edema,  effusion;  thoracic  duct;  right  lymphatic  duct;  principal  nodes; 
the  lymph  stream;  hyperemia,  metastasis;  physiology  of  lymph  system; 
clinical  notes 221 

CHAPTER  XIV 
THE  RESPIRATORY  ORGANS  AND  RESPIRATION 

The  respiratory  tract;  the  nose,  nares  and  choanae;  the  larynx;  trachea,  bronchi 
and  bronchial  tubes;  ciliated  epithelium;  air  cells;  the  lungs;  the  pleurae; 
respiratory  movements;  physiology  of  respiratory  organs;  ventilation; 
respiration  and  heat  production;  modifications  of  breathing;  clinical  notes.  231 

CHAPTER  XV 
ELIMINATION 

Organs  of  elimination;  the  kidney;  structure  of  the  kidney;  urinary  bladder;  ure- 
thral  caruncle;  physiology  of  the  kidney;  urine;  excretion  of  urine;  quantity 
and  variations;  importance  of  the  process;  nephritis;  albuminuria;  renal  casts; 
malposition  of  kidney;  floating  kidney 244 

CHAPTER  XVI 
ELIMINATION  (Continued) 

The  skin;  structure  of  the  skin;  layers;  epidermis  and  derma,  or  cuticle  and 
corium;  papillae;  vascularity  of  skin;  elasticity;  sensibility;  panniculus  adipo- 
sus;  glands  of  skin;  appendages;  hair;  nails,  structure  of;  physiology  qj^skin; 
protective;  excretory;  organ  of  sense  of  touch;  importance  of  perspiration; 
evaporation;  diaphoresis 253 

CHAPTER  XVII 
MAMMARY  GLANDS.    DUCTLESS  GLANDS  OR  ENDOCRIN  SYSTEM 

Structure  of  mammary  gland;  milk;  colostrum;  mammary  abscess;  ductless 
glands  and  internal  secretions  or  autocoid  substances;  hormones,  chilones; 
the  spleen,  structure  and  blood  supply;  leukemia;  the  pancreas  structure 
and  blood  supply;  adrenals,  adrenalin;  thyroid  body;  cretinism;  thymus 
body  an  infantile  structure;  pituitary  body  or  hypophysis;  chromaflfin  tissues.  260 


XII  CONTENTS 

CHAPTER  XVIII 
METABOLISM 

Secretion  and  secreting  organs;  excretion  and  excreting  organs;  general  metabo- 
lism; uses  of  food;  values  in  metabolism;  calorific  value;  diet  charts;  influ- 
ences effecting  metabolim;  animal  heat;  heat  production;  heat  dissipation; 
range  of  normal  temperature;  preservation  of  heat 269 

CHAPTER  XIX 
THE  NERVE  SYSTEM 

Two  divisions  of  the  nerve  system,  cerebro-spinal  and  sympathetic;  the  neuron, 
cell  body  and  nerve  fiber;  cerebro-spinal  division;  gray  and  white  nerve 
tissues;  nerve  centers;  spinal  cord  and  membranes;  structure  of  spinal 
nerves;  surgical  and  clinical  notes 277 

CHAPTER  XX 
THE  SPINAL  NERVES 

Anterior  and  posterior  divisions;  the  cauda  equina;  cervical  plexus,  phrenic 
nerve;  brachial  plexus,  radial,  ulnar  and  median  nerves;  lumbar  plexus, 
femoral  nerve;  sacral  plexus,  sciatic  nerves 284 

CHAPTER  XXI 
THE  BRAIN  AND  CRANIAL  NERVES 

Structure  of  brain,  cortex  and  fibers;  fissures;  ganglia;  internal  capsule;  cere- 
bellum; medulla  oblongata;  pons;  crura;  ventricles  of  brain;  membranes  of 
brain;  cranial  nerves;  physiology  of  brain  and  cranial  nerves;  cerebral 
localization,  surgical  and  clinical  notes 299 

CHAPTER  XXII 
THE  SYMPATHETIC  DIVISION  OF  THE  NERVE  SYSTEM 

Vertebral  ganglia;  cardiac  and  splanchnic  nerves;  cardiac  and  celiac  (solar) 
plexuses;  semilunar  ganglia;  functions  of  sympathetic  nerves;  vasomotor 
and  reflex,  presiding  over  visceral  action;  functions  of  nerve  system  as  a 
whole;  Important  notes;  Summary 316 

CHAPTER  XXIII 
THE  SPECIAL  SENSES 

General  and  special  sensation;  the  sense  of  smell,  olfactory  region;  the  sense  of 
touch,  touch  corpuscles;  the  sense  of  taste,  taste  buds;  the  sense  of  hearing, 
external  ear  and  auditory  canal;  middle  ear  or  tympanum  and  auditory 
tube;  internal  ear  or  labyrinth;  acoustic  nerves 325 


CONTENTS  Xlll 

CHAPTER  XXIV 
THE  SENSE  OF  SIGHT.    THE  VOICE 

The  sense  of  sight;  structure  of  eyeball;  myopia;  hyperopia;  astigmatism;  range 
of  accommodation;  eyelids,  lacrimal  gland;  associated  movements;  the 
voice;  vocal  cords;  organs  of  speech 335 

CHAPTER  XXV 
THE  PELVIC  ORGANS 

Organs  of  male  pelvis;  of  female  pelvis;  the  uterus;  uterine  or  Fallopian  tubes; 
the  ovaries,  ovulation;  corpus  luteum;  menstruation;  the  menopause;  the 
vagina  and  infra- vaginal  portion  of  cervix  uteri;  the  pudendum;  the  peri- 
neum; the  testes  and  spermatic  cord;  peritoneum  of  pelvis;  impregnation; 
decidual  membranes;  placenta;  pregnancy;  the  lochia 346 

CHAPTER  XXVI 
A  BRIEF  STUDY  OF  IMPORTANT  REGIONS 

The  head;  the  neck;  thorax  and  thoracic  viscera;  abdomen,  abdominal  viscera 
and  peritoneum;  the  ischio-rectal  fossa;  the  axillary  space;  the  ante-cubital 
space;  Scarpa's  triangle  or  the  femoral  trigone;  Hunter's  canal  or  the  ad- 
ductor canal;  the  popliteal  space;  the  inguinal  rings  and  inguinal  canal; 
the  femoral  rings  and  femoral  canal;  hernia;  the  extremities  compared; 
review  notes;  points  for  compression  of  larger  arteries  of  the  body 360 

CHAPTER  XXVII 
REFERENCE  TABLES 

The  systemic  arteries;  names  of  systemic  arteries  and  veins  according  to  the 

B.  N.  A 379 

Glossary 380 

Index 401 


ANATOMY  AND  PHYSIOLOGY 


INTRODUCTORY 

Anatomy  deals  with  the  structure  of  the  body  in  its  different 
parts;  physiology  teaches  the  uses  or  functions  of  those  parts. 

PLAN  OF  STUDY 

We  shall  study  first  the  framework  of  the  body — the  bones 
which  give  support  to  all  other  structures,  with  the  joints  by 
which  they  are  held  together,  either  loosely  or  firmly;  and  the 
muscles  by  which  they  are  moved  and  still  further  connected. 

Afterward  will  be  presented  the  organs  or  viscera  (which  are 
enclosed  in  the  two  general  cavities  formed  by  the  bones  and 
muscles)  with  their  nerve  supply,  and  the  system  of  vessels  by  which 
the  entire  body  receives  its  nutriment.  We  shall  see  that  all 
these  parts  are  wrapped  in  delicate  connective  tissue,  and  held 
in  place  by  bands  and  sheaths  of  the  same  substance.  The  mus- 
cles are  stretched  upon  the  bones,  the  firm  layers  and  partitions 
of  deep  fascia  bind  them  in  place,  the  wrapping  of  superficial 
fascia  keeps  them  warm  and  flexible,  and  the  skin  or  integument 
makes  an  elastic  and  sufficient  covering  for  the  whole. 

The  study  of  the  nerves  by  which  these  structures  receive 
their  stimulus,  and  the  action  and  interaction  of  the  various 
parts,  will  follow. 

The  organs  of  the  special  senses  receive  attention,  and  the  last 
section  is  devoted  to  a  review  of  the  several  regions  of  the  body 
which,  it  is  hoped,  will  prove  interesting  and  profitable. 

ANATOMIC  USE  OF  TERMS 

The  anatomic  position  is  that  with  the  face  toward  the  ob- 
server and  the  palms  turned  forward,  and  the  terms  anterior, 
posterior,  right,  left,  etc.,  are  to  be  understood  with  this  position 


2  ANATOMY  AND   PHYSIOLOGY 

in  mind.  Thus,  the  anterior  surface  of  the  hand  is  always  the 
palm;  and,  if  we  speak  of  any  part  as  situated  to  the  right  we 
mean  that  it  is  nearer  to  the  right  side  of  the  body  which  we  are 
studying  (which  for  convenience  we  will  call  the  " subject")? 
but  it  has  no  relation  whatever  to  the  right  side  of  the  student. 
Of  course  the  words  superior  and  inferior  are  easily  understood, 
but  the  use  of  the  words  medial  and  lateral  (formerly  internal 
and  external)  requires  special  mention.  Imagine  a  line  drawn 
through  the  middle  of  the  head  and  trunk  and  striking  the  floor 
between  the  feet,  thus  dividing  the  body  into  right  and  left 
halves.  This  is  called  the  median  line.  Any  part  or  surface  of 
one-half  of  the  body  is  said  to  be  medial  to  another  part  if  it  is 
nearer  the  median  line  while  in  the  anatomic  position,  or  lateral 
to  another  part  if  it  is  farther  from  the  median  line. 

All  of  these  terms  once  applied  to  a  part  of  the  body  belong  to 
it  always.  For  example,  the  little  finger  is  always  medial  to  the 
others  and  the  great  toe  is  likewise  medial,  because  these  relations 
are  established  once  for  all  while  the  subject  is  in  the  anatomic 
position.  Likewise,  the  palm  is  the  anterior  surface  of  the  hand 
even  if  it  be  temporarily  turned  backward. 

The  words  exterior  and  interior  are  applied  to  the  parts  of  the 
body  which  are  on  the  surface  or  within,  respectively. 

Proximal  means  nearer  to  the  head;  distal,  farther  from  the 
head.  Thus  we  may  speak  of  the  proximal  end  of  the  finger,  or 
the  distal  end  of  a  toe,  or  the  proximal  end  and  distal  end  of  an 
arm  or  a  leg. 

Certain  words  have  been  so  long  applied  in  a  special  sense  in 
connection  with  anatomic  relations  and  physiologic  processes 
that  usage  has  made  them  technical,  that  is,  they  have  come  to 
possess  a  professional  meaning. 

Hilum  (literally  a  little  thing)  is  applied  to  a  place  on  the 
surface  of  an  organ;  a  depression  usually,  where  the  vessels  and 
nerves  enter  and  leave  it.  Thus,  we  see  the  hilum  of  the  kidney, 
of  the  lung,  of  the  spleen.  The  hilum  is  always  found  on  the 
medial  or  most  protected  surface  of  an  organ.  (In  the  case  of  the 
liver  it  is  on  the  inferior  surface  and  is  called  the  porta  or  gateway.} 

Sinus  (literally  a  hollow  or  indentation)  is  applied  in  anatomy 
to  a  hollow  or  enlarged  space  within  an  organ,  containing  either  air 
or  fluid.  Air  sinuses  are  hollow  spaces  (almost  enclosed),  con- 


TECHNICAL   USE   OF   TERMS  3 

nected  with  the  nasal  passages;  these  are  cavities  in  the  cranial 
and  facial  bones.  Lymph  sinuses  are  the  spaces  within  lymph 
glands.  They  contain  lymph  (in  some  glands — blood).  Sinuses 
containing  fluid  are  large  channels  in  the  outer  membrane  of  the 
brain — containing  venous  blood.  Other  blood  sinuses  are  found  in 
the  heart.  The  sinus  of  the  kidney  is  the  hollow  which  is  reached 
through  the  hilum  which  leads  into  it;  this  contains  urine.  In 
surgery  a  sinus  is  a  narrow  abnormal  channel  through  the 
tissues  (usually  lined  by  or  connected  with  an  ulcerating  surface). 
Center  and  periphery  are  so  used  (technically)  in  connection 
with  the  nervous  system.  The  center  is  the  cell  or  cells  to  which 
a  nerve  must  belong  and  be  connected  with  in  order  to  be  active. 
It  need  not  necessarily  be  in  the  middle  of  a  part — some  of  the 
most  important  centers  are  on  the  surface  of  the  brain.  The 
periphery  is  the  location  of  the  extremity  of  the  nerve.  Literally 
it  signifies  the  outer  boundary  or  the  outside  of  a  thing,  but  when 
used  in  connection  with  a  nerve  it  refers  to  the  end  farthest  from 
the  cell  or  center,  whether  within  or  without  the  body. 

Centrifugal  nerves  transmit  from  center  to  periphery  (they  are  efferent). 
Centripetal  nerves  transmit  from  periphery  to  center  (they  are  afferent}. 
Efferent  vessels  carry  blood  from  organs;  afferent  vessels  carry  blood  to 
organs. 

Stimulus  in  physiology  signifies  any  agency  which  causes  a 
tissue  or  an  organ  to  perform  its  function.  A  natural  stimulus  is  a 
normal  exciting  cause  and  leads  to  normal  action  or  function. 

An  element  is,  in  chemistry,  a  substance  which  cannot  be 
divided  into  other  substances.  The  most  important  elements  in 
the  human  body  are  comparatively  few.  They  will  be  referred  to, 
sometimes  by  name,  sometimes  by  symbol.  By  agreement, 
certain  letters  stand  for  certain  elements  (usually  the  initials  of 
their  Latin  names). 

0  is  the  symbol  for  Oxygen 

H  is  the  symbol  for  Hydrogen 

N  is  the  symbol  for  Nitrogen 

C  is  the  symbol  for  Carbon 

S  is  the  symbol  for  Sulphur 

Fe  is  the  symbol  for  Iron  (Ferrum) 

P  is  the  symbol  for  Phosphorus 

K  is  the  symbol  for  Potassium  (Kalium) 

Na  is  the  symbol  for  Sodium  (Natrium) 


4 


ANATOMY  AND   PHYSIOLOGY 


(Combinations  frequently  used  are  C02  for  carbon  dioxide  or 
"carbonic  acid  gas"  H^O  for  water.} 

Food  principles  are  simple  or  compound  substances,  composed 
of  one  or  several  elements.  They  are  broadly  classed  as,  i.  con- 
taining nitrogen ,  nitrogenous,  2.  without  nitrogen,  non-nitrogenous, 
and  3.  containing  only  mineral  substances. 

TISSUES  AND  MEMBRANES  OF  THE  BODY 

The  simplest  form  of  living  matter  is  protoplasm.  A  living  cell 
may  be  nothing  more  than  a  definite  quantity  of  protoplasm 
(called  cytoplasm  or  bioplasm)  or  it  may  be  more  complex,  having 
a  nucleus,  when  it  is  said  to  be  nucleated,  and  it  may  have  a 
nucleolus  within  the  nucleus.  A  nucleated  cell  is  capable  of  form- 
ing new  cells  by  the  division  of  its  substance,  the  division  always 
beginning  in  the  nucleus. 

Sometimes  the  cell  is  enveloped  by  a  thin  membrane  called  the  cell  wall. 


FIG.  i. — CONNECTIVE-TISSUE 
BUNDLES  OF  VARIOUS  THICK- 
NESSES OF  THE  INTERMUSCULAR 
CONNECTIVE  TISSUE  OF  MAN. 
X  240. — (Lewis  and  Stohr.} 


Fat-cells 

io  a 
simple 
layer 


FIG.  2. — ADIPOSE  TISSUE. — (Lewis 
and  Stdhr.) 


Tissue. — Any  collection  of  cells  held  together  by  intercellular 
substance  is  a  tissue.  The  various  tissues  of  the  body  are  com- 
posed of  cells  (and  intercellular  substance)  which  are  developed  in 
special  ways;  for  example: 

Muscle  tissue  is  composed  largely  of  cells  which  are  highly 
developed  in  the  power  to  contract.  Contractile  tissues  (list,  p.  83). 


CONNECTIVE   TISSUE  5 

Nerve  tissue,  of  cells  which  are  particularly  sensitive  to 
special  kinds  of  stimulus. 

Connective  tissue  is  the  fibrous  soft  framework  of  the  entire 
body — the  connecting  structure  by  means  of  which  all  of  its  parts 
are  held  together.  (Fig.  i.) 

Under  this  heading  are  included  the  following  varieties: 
Fibrous  tissue,  a  form  of  connective  tissue  containing  slender 

white  fibers,  closely  packed  together. 
Areolar  tissue,  containing  the  same  kind  of  fiber  cells  loosely 

woven  into  a  network  (often  called  cellular  tissue). 
Adipose  tissue,  a  variety  of  areolar  tissue  with  cells  containing 
fat.     (Fig.  2.) 


FIG.  3.— ELASTIC  FIBERS.     Xs6o.     Very  thick  elastic  fibers  /,  from  ligamentum 
nuchaeof  ox;  b,  connective-tissue  bundles. — (Lewis  and  St'ohr.} 

Elastic  tissue,  a  form  of  connective  tissue  containing  many 
elastic  fibers,  pale  yellow  in  color.  (Fig.  3.) 

Osseous  tissue,  composed  largely  of  cells  having  the  power  to 
utilize  mineral  substances  of  the  blood  in  the  formation 
of  bone.  (The  intercellular  substance  is  filled  with  min- 
eral matter.)  (Figs.  7  and  8.) 

Cartilage,  a  form  of  connective  tissue  with  firm  white  elastic 
substance  (intercellular  substance)  between  its  cells. 
Many  cartilages  are  covered  with  a  thin  membrane 
called  perichondrium,  similar  to  the  periosteum  of  bones 
(seepage  13). 


ANATOMY  AND   PHYSIOLOGY 


The  principal  varieties  are: 

Hyaline  cartilage  which  has  few  cells  and  much  intercellular  sub- 
stance.    (Fig.  4.) 
While  fibro-cartilage  which  contains  many  white  fibers,  giving  to  it 

additional  strength. 

Yellow  or  elastic  fibro-cartilage  which  contains  elastic  fibers  giving  ad- 
ditional elasticity. 
Note. — Most  bones  are  formed  in  cartilage.     (See  Ossification,  page  14.) 


Epithelial  tissue  forms  the  surface  layers 
of  the  body  both  within  and  without.  It  is 
composed  of  layers  of  cells  resting  upon  a  base 
of  the  simplest  possible  substance,  which  holds 
the  cells  together  and  which  bears  vessels  and 
nerves  for  their  use.  The  form  of  epithelial 
cells  varies  with  their  location  and  use  or  func- 
tion. (Fig.  5.) 

The  epithelium  of  the  exterior  of  the  body  is 
formed  by  flattened  cells,  arranged  in  few  or 
many  layers  according  to  the  degree  of  friction  or  pressure  to 
which  the  skin  of  the  part  may  be  exposed.  The  covering  thus 
formed  varies  therefore  in  thickness,  from  that  of  the  delicate 
covering  of  the  lips  to  the  tough  sole  of  the  foot. 


FIG.  4. — HYALINE 
CARTILAGE.— (Stohr.) 


FIG.  5. — EPITHELIAL  CELLS  OF  RABBIT,  ISOLATED.  Xs6o.  i.  Squamous  cells 
(mucous  membrane  of  mouth).  2.  Columnar  cells  (corneal  epithelium).  3.  Columnar 
cells  with  cuticular  border  5  (intestinal  epithelium).  4.  Ciliated  cells;  h,  cilia 
(bronchial  epithelium). — (Lewis  and  Stohr.} 

The  epithelium  of  interior  surfaces  is  quite  different.  Its  cells 
may  be  flattened,  spherical,  cuboid  or  columnar  in  shape  and  it  is 
always  moist.  (All  body  surfaces  are  epithelial  surfaces.) 

In  the  lining  of  the  air  passages  the  epithelial  cells  are  ciliated,  that  is, 
they  bear  tiny  hair-like  projections  of  their  substance  called  cilia,  which  are 
in  constant  waving  motion,  always  in  the  same  direction,  sometimes  slow, 
sometimes  rapid.  (See  p.  235.) 


EPITHELIAL   TISSUES  7 

In  the  digestive  organs  the  epithelial  layer  plays  an  important  part  in  the 
formation  of  digestive  fluids,  and  also  in  the  absorption  of  digested  food. 

In  the  lining  of  closed  cavities  it  assists  in  the  formation  of  the  fluids  which 
they  contain  (example,  the  pleura}. 

Included  under  this  heading  are  (with  brief  notes  of  functions) : 
Gland  tissue,  where  a  layer  of  cells  has  the  power  to  form 
a  special  substance  from  the  blood.  (Adenoid  tissue 
resembles  gland  tissue.)  (See  p.  8.) 

Mucous  membranes,  which  line  all  interior  surfaces  to  which 
air  has  access.  Their  special  cells  produce  a  clear  thick 
fluid  called  mucus  which  keeps  the  surfaces  moist. 

Serous  membranes,  which  line  the  closed  cavities  of  the  body. 
They  are  themselves  closed  sacs  containing  a  clear  thin 
fluid  called  serum  which  prevents  the  surfaces  from 
rubbing  together. 

Synovial  membranes,  which  line  the  interior  of  movable  joints; 
they  contain  a  thick  fluid  called  synovia  which  like  serum 
prevents  friction. 

The  epithelial  lining  of  the  heart  and  blood-vessels,  serous  membranes, 
and  lymph  vessels,  is  called  endothelium. 

Clinical  notes. — Mucous  membranes  are  well  supplied  with  blood-vessels 
and  bleed  freely  when  wounded,  as  seen  in  operations  upon  the  nose  and 
throat. 

An  accumulation  of  serum  in  the  large  serous  membrane  of  the  abdomen 
causes  the  condition  called  asciles  (a  variety  of  dropsy). 

The  processes  of  secretion  and  excretion  are  carried  on  through 
epithelial  cells.  (In  specialized  epithelial  tissues.) 

Secretion  is  the  process  of  separating  substances  from  the  blood 
(generally  in  fluid  form).  Such  substances  if  useful  to  the  body 
are  called  secretions;  if  they  are  waste  matters  to  be  thrown  off  or 
eliminated,  they  are  called  excretions. 

Secreting  organs — mucous  and  serous  membranes,  all  glands. 

Excreting  organs — lungs,  kidneys,  liver,  cutaneous  glands. 

To  summarize  the  functions  of  epithelial  tissues — they  are 
protective,  secretory,  excretory,  absorptive. 

An  organic  substance  is  a  substance  formed  by  living  cells, 
whether  they  are  single  or  arranged  together  in  organs.  Organic 
substances  disappear  in  burning.  Inorganic  substances  are  mineral. 


8  ANATOMY   AND   PHYSIOLOGY 

An  organ  is  any  part  of  the  body  designed  for  a  special  func- 
tion or  use;  it  may  be  composed  of  several  kinds  of  tissue.  An 
organ  in  the  interior  of  the  body  (internal  organ)  is  called  a 
viscus  (pleural,  viscera).  •  Examples,  heart,  lungs. 

A  system  is  composed  of  a  number  of  organs  of  similar  structure. 
Examples,  the  muscular  system,  the  nervous  system. 

An  apparatus  is  composed  of  a  number  of  organs  of  like  or 
different  structures,  so  arranged  and  associated  that  their  action 
together  will  serve  a  special  purpose.  Example,  the  digestive 
apparatus. 

Metabolism. — This  term  is  used  to  express  in  one  word  the 
related  processes  of  building  up  and  breaking  down  which  are 
constantly  going  on  in  all  living  cells. 

The  cell  appropriates  materials  and  combines  them  to  perfect 
itself;  in  the  exercise  of  its  function  it  uses  up  some  portion  of  its 
substance  and  so  must  be  again  built  up,  to  be  again  pulled  apart 
— in  endless  repetition. 

Cell  action  in  some  tissues  results  principally  in  liberating  heat  and  in 
body  movement,  as  in  muscles.  In  others  it  forms  new  compounds  for  other 
cells  to  use — for  example,  the  liver  cells  form  glycogen;  the  gastric  glands 
secrete  gastric  juice,  etc.  Again,  certain  cells  combine  waste  matters  to  get 
them  into  shape  for  other  organs  to  excrete,  for  example,  the  formation  of 
urea  in  the  liver.  In  this  way  food  materials  are  used  for  different  purposes 
and  worked  over  in  different  tissues  until  waste  alone  remains. 

These  examples  (and  many  more  which  might  be  given)  illustrate  the 
metabolism  which  is  constantly  taking  place  in  the  body,  and  which  will 
often  be  referred  to  in  the  text.  (See  pp.  166,  271.) 

Structure  of  Glands:  Since  gland  tissue  is  so  important 
a  factor  of  vital  processes,  a  further  description  is  warranted. 
It  has  already  been  stated  that  the  epithelial  layer  is  the  active 
agent  in  the  formation  of  new  substances  out  of  material  derived 
from  the  blood.  For  the  performance  of  this  function,  the 
epithelium  is  disposed  in  organs  called  glands. 

The  simplest  gland  is  either  a  small  tube,  or  a  sac.  The 
tubular  gland  may  be  divided  into  two  or  more  portions  forming 
a  compound  tubular  gland.  Tubular  glands  exist  in  the  stomach, 
intestines,  skin,  etc.;  in  the  skin  they  are  coiled  or  convoluted  at 
the  extremity.  (See  Fig.  166.)  A  modification  of  the  saccular 
gland  is  one  which  is  composed  of  many  small  sacs  arranged  like 


GLAND   TISSUES  9 

a  bunch  of  grapes  upon  their  stem — racemose  gland.  The  salivary 
and  pancreatic  glands  resemble  this  form. 

The  secretion  of  a  true  gland  is  discharged  through  a  duct 
which  opens  upon  some  surface,  either  of  the  exterior  or  the  in- 
terior of  the  body — for  instance,  the  sweat  glands  open  upon  the 
skin,  the  gastric  glands  open  upon  the  interior  surface  of  the 
stomach,  etc.  All  secretions  which  are  discharged  through  ducts 
of  glands  are  called  external  secretions.  (For  internal  secretions 
see  page  263.) 

Lymphoid  tissues  are  so  called  because  they  contain  lymph 
cells  supported  in  a  network  of  retiform  tissue.  The  faucial  or 


Excretory  duct. 


Secretory  duct. 


Intercalated  duct. 


End  pieces. 


FIG.  6 — DIAGRAM  OF  VARIOUS  FORMS  OF  GLANDS. — (Lewis  and  Stohr.) 
The  arrangement  of  ducts  in  D  is  that  of  the  human  submaxillary  gland. 

palatine  tonsils  are  lymphoid  in  structure  (page  133),  as  are 
also  the  lingual  and  thenaso-pharyngeal  tonsils  (page  135).  (Ade- 
noids are  hypertrophied  naso-pharyngeal  tonsils.) 

Blood  and  lymph,  although  quite  different  in  composition  from 
others,  still  conform  to  the  definition  of  a  tissue  and  are  called 
fluid  tissues.  They  are  each  composed  of  an  assemblage  of  small 
cells  supported  by  intercellular  substance;  in  this  case,  the  inter- 
cellular substance  is  fluid  instead  of  solid  or  semi-solid.  In  blood, 


10  ANATOMY  AND   PHYSIOLOGY 

the  cells  are  blood  corpuscles;  in  lymph,  they  are  lymph  corpuscles. 
The  intercellular  substances  are  blood  plasma  and  lymph  plasma. 
(Other  fluids  contain  chemical  substances  only,  in  solution;  cells 
appear  in  them  incidentally.) 

These  tissues  will  be  described  more  at  length  in  Chapters 
X  and  XIII. 


CHAPTER  I 


BONE  TISSUE  AND  BONE  CLASSIFICATION 
ARTICULATIONS 


Bone  tissue  is  conspicuously  a  hard  tissue, 
due  to  the  mineral  or  inorganic  substances 
which  it  contains.  They  are  mostly  -phosphate 
and  carbonate  of  lime  and  form  two- thirds  of 
the  weigniroi  an  adult  bone. 


The  remaining 

one-third  is  composed  of  organic  or  animal 
substances,  consisting  of  vessels,  marrow,  bone 
corpuscles,  and  gelatinous  matter. 

The  mineral  portion  alone  may  be  seen  in 
a  bone  which  has  been  burned  (thus  destroy- 
ing the  organic  substances).  This  leaves  the 
bone  still  hard,  but  very  brittle  and  easily 
crushed.  The  pale  grayish  color  of  a  burned 
bone  is  noticeable,  the  result  of  the  loss  of  all 
the  marrow  and  blood  .which  it  contained  be- 
fore, and  which  gave  it  a  pinkish  tinge. 

The  organic  portion  of  a  bone  may  be 
shown  by  immersing  it  in  dilute  hydrochloric 
acid  for  a  few  days.  The  mineral  salts  will 
be  thus  dissolved  out,  leaving  the  flexible  and 
elastic  organic  portion  which  still  retains  the 
shape  of  the  bone.  A  long  bone  after  the 
lime  salts  are  removed  in  this  way  is  said  to  be 
decalcified,  and  may  be  bent  and  twisted,  or 
even  tied  in  a  knot. 

By  these  experiments  it  is  seen  that  the 
mineral  matter  gives  hardness  to  a  bone, 
while  the  animal  matter  gives  flexibility  and 
elasticity.  The  proportions  of  the  two  kinds 
of  substance  vary  at  different  ages 
bones  of  a  child  are  soft  because  they  have  not 


This  hardness  is 


FIG.   7. — VERTICAL 
Xhe    SECTION    OF    A   LONG 
BONE. — (Testut.} 


12 


ANATOMY  AND   PHYSIOLOGY 


enough  mineral  matter  to  make  them  hard,  while  the  bones  of 
an  aged  person  are  brittle,  because  they  no  longer  contain  suffi- 
cient animal  matter  to  keep  them  elastic. 

The  hardest  part  of  any  bone  is  at  its  surface;  it  is  white  in 
color  like  ivory,  and  is  called  compact  bone  tissue.  The  deeper 
part  is  porous,  and  is  therefore  called  spongy  tissue  (also  named 
cancellous  tissue,  because  its  appearance  suggests  lattice  work). 
(See  Fig.  7.) 

Compact  tissue  is  most  abundant  on  the  shafts  of  the  long 
bones,  which  by  their  situation  in  the  extremities  are  exposed  to 
external  violence,  and  therefore  need  especial  strength  for  resist- 
ance. Since  it  is  important  that  the  bones  be  slender  as  well  as 
strong,  these  two  results  are  gained  by  packing  the  bone  tissue  as 
closely  as  possible. 


Periosteum 

Outer  ground  lamellae 

Haversian  canals 


Haversian  lamellae 

Interstitial  lamellae 
Inner  ground  lamellae 

Marrow 


FIG.  8. — FROM  A  CROSS-SECTION  OF  A  METACARP  OF  MAN.     X  50.     The  Haversian 
canals  contain  a  little  marrow  (fat-cells). — (Lewis  and  Stohr.) 

Cancellous  tissue  is  more  abundant  in  the  parts  of  bones  where 
extent  of  surface  is  desirable.  For  example,  the  enlarged  ex- 
tremities of  long  bones  are  composed  of  cancellous  tissue  covered 
with  a  thin  compact  layer;  thus  they  can  give  attachment  to  many 
tendons  and  ligaments,  while  the  spongy  character  of  the  bone 
prevents  excessive  weight. 

The  marrow  of  bones  is  contained  in  the  spaces  of  cancellous 
tissue  (where  it  is  thin  and  red)  and  in  little  canals  running  through 
the  bone  substance.  Under  the  microscope  may  be  seen  small 
channels  in  the  compact  tissue  called  Haversian  canals,  which  con- 
tain minute  vessels  and  a  little  marrow.  A  large  canal  called  the 


PERIOSTEUM  13 

medullary  canal  runs  in  the  shaft  of  each  long  bone,  containing 
firm  yellow  marrow  and  larger  vessels. 

Articular  surface  of  bone  is  that  portion  which  enters  into  the 
formation  of  a  movable  joint.  It  consists  of  a  very  compact 
tissue  called  the  articular  layer  or  articular  lamella. 

SURFACE  MARKINGS  OF  BONE 

Any  inequality  of  the  surface  of  a  bone,  whether  it  be  an 
elevation  or  depression,  or  an  opening,  is  called  a  "marking." 
The  most  prominent  elevations  often  occur  where  the  muscles  are 
attached  to  the  periosteum  (owing  partly  to  the  calcification  of 
these  attachments);  and  the  greatest  enlargements  of  bones  are 
at  their  extremities,  where  they  form  important  joints. 

A  process  is  a  decided  projection;  the  larger  processes  are  called 
tuberosities,  small  ones,  tubercles. 

A  spine  is  usually  a  long  or  a  sharp  projection. 

A  crest  is  a  prominent  border;  it  may  be  rather  broad. 

A  condyle  is  a  rounded  articular  eminence. 

A  fossa  is  a  depression  or  concavity. 

A  foramen  is  a  hole  through  a  bone. 

PERIOSTEUM 

There  is  no  such  thing  as  bare  bone  in  the  normal  state;  all 
bones  are  closely  covered  more  or  less  completely  with  a  strong 
fibrous  membrane  called  periosteum.  This  membrane  is  essential 
to  the  life  of  the  bone,  rjecause  many  blood-vessels  which  nourish 
it  lie  in  the  periosteum  until  they  become  divided  into  minute 
branches  which  then  enter  the  bone  tissue. 

The  articular  surface  of  bone  is  the  only  portion  which  is  not 
covered  with  periosteum. 

A  bruise  of  sufficient  violence  will  so  injure  the  periosteum  that 
it  no  longer  serves  for  the  purpose  of  nutrition,  and  that  area  of 
bone  immediately  underneath  the  injured  membrane  dies  from 
want  of  food — becomes  "dead  bone"  (the  process  is  called 
necrosis}.  The  sensation  imparted  by  a  probe  which  touches 
dead  bone  is  that  of  roughness,  and  is  distinctly  different  from  the 
feeling  of  sound  bone  with  its  smooth  covering  of  periosteum. 


14  ANATOMY   AND   PHYSIOLOGY 

A  similar  membrane  called  endosteum  lines  the  canal  in  the  shaft 
of  long  bones.  It  bears  the  " nutrient"  artery  which,  in  the  cavity 
of  the  shaft,  divides  into  two  branches  running  in  the  endosteum 
toward  the  two  extremities. 

The  deep  layers  of  the  periosteum  contain  bone-forming  cells. 
(See  OSSIFICATION.) 

CLASSIFICATION  OF  BONES  ACCORDING  TO  SHAPE 

According  to  differences  of  shape  and  arrangement  of  their 
tissue,  bones  are  classified  as  long,  short,  fiat,  and  irregular.  A 
long  bone  has  always  a  shajf  of  compact  tissue, 
and  two  enlarged  extremities  of  cancellous  tissue 
with  a  thin  compact  covering.  The  shaft  is  hol- 
low, containing  yellow  marrow,  this  cavity  being 
called  the  medullary  canal. 

A  short  bone  has  neither  shaft  nor  extremity; 
it  is  composed  of  cancellous  tissue  with  a  thin 
compact  covering. 

A  flat  bone  is  arranged  in  layers,  two  of  compact 
tissue  with  one  of  spongy  or  cancellous  tissue  be- 
tween them. 

An  irregular  bone  conforms  to  no  special  defi- 
nition. 

REMARKS. — In  no  part  of  anatomy  is  it  more  impor- 
tant that  the  student  should  learn  the  structures  from 
the  actual  specimens  than  in  the  division  called  osteology. 
The  bones  are  to  be  studied,  not  the  book.     It  is  supposed 
that  with  the  bone  in  the  hand  the  student  will  use  the 
FIG.  9.— RIGHT  book  as  a  key,  by  means  of  which  she  will  become  ac- 
FEMUR  ANTERIOR,  quainted    with    the  names  of    its  parts  and  their  uses. 
mE^ol  E£pTiPHY-  The  habit  of  studying  the  human  body  itself  rather  than 
SES,  AND  SHAFT  OR  the  description  of  it  cannot  be  too  soon  nor  too  firmly 

P'AP  =  YSIS-  ~~  established. 
(Morns.) 

OSSIFICATION 

Ossification  is  the  formation  of  bone  from  cartilage  or  mem- 
brane by  the  deposit  of  mineral  substances,  mostly  salts  of  lime. 
Flat  bones  develop  in  membrane;  others  in  cartilage. 


OSSIFICATION  1 5 

The  deposit  of  mineral  matter  begins  in  small  spots,  forming 
centers  of  ossification  which  gradually  increase  in  size  until  the 
entire  bone  is  completed.  Long  bones  have  always  three  centers 
at  first — one  for  the  shaft,  and  one  for  each  extremity — others 
appearing  later,  at  different  dates.  (The  extremities  are  named 
epiphyses,  the  shaft  being  the  diaphysis)  (see  Fig.  9).  The 
pTincipal  parts  of  a  bone  are  ossified  separately,  uniting  with 
each  other  after  all  are  developed.  Ossification  begins  before 
birth  in  all  bones  except  the  coccyx,  those  of  the  carpus,  and  four 
in  the  tarsus;  but  many  bones  remain  in  two  or  more  pieces 
during  childhood  and  youth. 

The  periosteum  of  bone  has  an  inner  layer  in  which,  also,  the 
process  of  ossification  goes  on.  Consequently,  when  it  becomes 
necessary  to  remove  a  portion  of  bone,  if  it  can  be  done  without 
taking  the  periosteum  away  the  bone  will  re-form.  This  has 
occurred  many  times,  particularly  in  the  case  of  the  mandible. 

The  nutrition  of  bone. — Bones  have  a  free  blood  supply  from 
a  network  of  small  arteries  in  the  periosteum.  One  special  artery, 
larger  than  the  others,  enters  the  nutrient  canal  which  leads  to 
the  interior  of  the  shaft  (this  vessel  is  called  the  nutrient  artery) . 

THE  HUMAN  SKELETON 

The  skeleton  of  the  body  comprises  200  bones,  as  follows: 

In  the  cranium 8 

In  the  face 14 

In  the  spinal  column 24 

In  the  pelvis 4 

In  the  upper  extremities 64 

In  the  lower  extremities 60 

Ribs 24 

Os  hyoides i 

Sternum. .                                              i 


200 

These  are  joined  together  or  articulated  to  form  the  hard, 
strong  framework  of  the  body — the  natural  skeleton. 

In  addition  to  these,  there  are  four  bones  in  each  ear  called  ossicles,  or 
"little  bones,"  malleus,  incus,  stapes  and  so-called  orbicular  bone. 


i6 


ANATOMY  AND   PHYSIOLOGY 


According  to  their  location  in  the  body  they  are  classified  as 
follows:  Bones  of  the  Head  and  Neck,  Trunk,  Extremities. 


Head 


Tibia 
Fibula 


Tarsus 

Metatarsus 

Phalanges 


FIG.  10. — BONY  SKELETON. — (Holden.) 

The  bones  of  the  head  form  the  skull,  which  supports  the  face 
and  the  organs  of  special  sense,  and  securely  encloses  the  brain 
within  its  cavity.  The  bones  of  the  neck  connect  the  head  with 
the  trunk,  and  support  the  tongue  and  various  other  structures. 


ARTICULATION   OF  BONES 


The  bones  of  the_trjmfc  assist  to  form  a  cavity,  divisible  into 
three  portions — the  thorax,  the  abdomen,  and  the  pelvis. 

The  bones  of  the  four  extremities  contribute  the  solidity  and 
strength  which  are  necessary  for  their  uses  in  various  positions  of 
the  body. 

ARTICULATIONS  (ARTHROSES) 

Articulations  are  formed  when  two  or  more  bones  are  con- 
nected together,  or  when  bone  and  cartilage  are  joined.  They 
may  be  immovable  or  movable. 


IMMOVABLE  JOINTS  (SYNARTHROSES) 

In  these  the  bones  are  held  to- 
gether firmly  by  fibrous  tissue,  some- 
times by  a  thin  layer  of  cartilage  which 
becomes  calcified  in  later  life. 

The  best  examples  of  immovable 
joints  are  found  in  the  skull,  where 
the  flat  bones  are  joined  at  their  edges, 
forming  sutures.  (See  page  20,  Fig.  12.) 

MOVABLE  JOINTS  (DIARTHROSES) 

In  these  the  bones  are  not  closehi 
joined,  but  are  loosely  connected  by 
ligaments  which  allow  freedom  of  move- 
"ment  between  the  surfaces.  They  are 
best  studied  in  the  extremities,  where  ™RES  IN  A  MOVABLE  JOINT. 

.    .  (Diagrammatic.) 

all    varieties    of    movable    joints    are 
found. 

.  The  essential  structures  in  a  movable  joint  are  four  in  num- 
ber: Articular  bone,  articular  cartilage,  ligaments,  synovial  mem- 
brane with  synovia. 

The  surfaces  of  bone  which  are  to  be  connected  together 
(articular  surfaces)  are  made  of  a  specially  hard  compact  tissue 
called  articular  bone.  It  is  smoother  than  other  portions  of  the 
bone  and  easily  recognized  by  the  eye.  It  has  no  periosteum,  but 
is  covered  by  firm  white  hyaline  cartilage — the  articular  cartilage. 


1 1. — ILLUSTRATION 
ESSENTIAL     STRUC- 


1 8  ANATOMY   AND   PHYSIOLOGY 

To  hold  the  bones  together,  bands  or  cords  of  white  fibrous 
tissue  are  provided,  strong  and  flexible,  but  not  elastic.  They 
are  called  ligaments.  The  ligaments  pass  from  one  bone  to 
the  other  on  every  side  of  the  joint,  like  a  capsule,  completely 
enclosing  it,  and  the  capsule  thus  formed  is  lined  by  synomal 
membrane.,  so  named  because  it  secretes  a  fluid  called  s 
(the  lubricating  fluid  or  "joint-oil")  which  resembles  in  appear- 
ance the  white  of  egg  and  prevents  friction. 

The  synovial  membrane  not  only  lines  the  capsule  but  is 
attached  to  the  margins  of  the  articular  cartilages. 

Seven  varieties  of  movement  are  allowed  by  these  joints. 
They  are: 

Flexion,  or  bending. 

Extension,  or  straightening. 

Rotation,  or  rolling. 

Circumduction,  a  free  sweeping  movement  of  the  distal  end 
of  a  limb  in  a   circle. 

Abduction,  or  moving  away  from  a  middle  line. 

Adduction,  or  moving  toward  a  middle  line. 

Gliding  (which  explains  itself). 

Movable  joints  are  classified  according  to  the  movements  of 

ividual  joints,   or  by  peculiarities   of   structure.     The  most 
important  are  the  following: 

Class.  Motions.  Example. 

Hinge  (ginglymus) Flexion  and  extension. . . .  Elbow,  Knee. 

Ball  and  socket  (Enar- 

throsis) In  all  directions Shoulder,  Hip. 

Pivot  (Trochoides) Rotation  within  a  ring Head  of  Radius. 

Rotation  of  ring  around  a 

pivot A  lias  and  axis. 

Arthrodia Gliding Wrist  joints. 


There  are  other  joints  in  which  motion  is  so  slight  that  they 
are  not  classed  as  movable,  nor  do  they  possess  a  cavity  containing 
synovia.  They  have  been  well  described  by  the  term  yielding. 
In  these  the  bones  are  usually  connected  by  fibro-cartilage  discs. 
Examples  are  found  in  the  joints  of  the  pelvis  (page  50)  and  in 
the  spinal  column  (page  42).  They  are  sometimes  classified  as 
slightly  movable. 


PECULIAR   JOINTS  1 9 

A  variety  of  ball  and  socket  joint  is  the  condyloid,  where  the  surfaces  have 
an  oval  instead  of  a  round  outline;  they  allow  all  motions  except  rotation. 

Another  is  the  saddle-joint.  Each  surface  has  both  a  concavity  and  a 
convexity  and  each  receives  the  other.  (See  page  63,  Surgical  Note  No.  2.) 


CHAPTER  II 
BONES  AND  ARTICULATIONS  OF  THE  SKULL 

The  skull  includes  the  cranium  and  face. 

BONES  OF  THE  CRANIUM,  8 

Frontal i  Parietal 2 

Occipital i  Ethmoid i 

Temporal 2  Sphenoid i 

Frontal  bone  (os  frontale) . — In  the  anterior  part  of  the  skull, 
shaped  like  a  cockle-shell,  and  consisting  of  the  frontal  part,  or 
forehead,  the  two  orbital  parts,  and  the  nasal  part.  The  frontal 


GLABEL 


ANTERIOR    NASA 
SPINE 


GNATHIO 


BELION 


MBDA 


FIG.  12. — THE  SKULL.— (Gerrish.) 

part  (squama  frontalis)  is  flat  in  structure,  and  unites  above  with 
the  parietal  bones.  This  part  is  bounded  below  by  a  prominent 
border  forming  the  two  supraorbital  margins.  At  the  medial 


FRONTAL   AND    OCCIPITAL  BONES 


21 


third  of  each  margin  is  a  supra  orbital  notch  (sometimes  foramen) 
for  the  supraorbital  nerve,  artery,  and  vein.  Just  above  the 
margins  are  the  superciliary  arches,  which  bear  the  eyebrows  and 
mark  the  position  of  spaces  in  the  frontal  bone  called  the  frontal 
sinuses.  These  sinuses  begin  to  develop  at  the  age  of  seven  years 
and  grow  larger  as  time  advances.  They  communicate  with  the 
nose,  and  contain  air.  The  smooth  space  between  the  eyebrows 
is  the  glabella. 

The  nasal  part  is  just  below  the  glabella. 

The  orbital  parts  (or  plates)  of  the  frontal  bone  are  so  called 
because  they  are  in  the  roof  of 
the  orbits,  or  eye-sockets;  the 
space  between  these  parts  is 
occupied  by  the  ethmoid  bone 
and  is  called  the  ethmoid  notch. 
Just  underneath  the  lateral  part 
of  the  superior  margin  of  the 
orbit  is  a  small  fossa  (the  lacri- 
mal fossa),  containing  the'lacri- 
mal  gland,  where  the  tears  are 
formed. 

At  birth  the  frontal  bone  is 
in  halves — right  and  left — 
which  become  united  in  early 
life. 

Occipital  bone  (os  occipitale). — At  the  back  of  the  skull  and 
consisting  of  two  portions:  squamous  (scale-shaped)  and  basal 
(Figs.  12  and  21). 

The  squamous  portion  (squama  occipitalis)  is  flat  in  structure, 
triangular  in  shape,  arid  joined  to  the  parietal  bones.  The  most 
prominent  point  on  the  back  of  the  skull  is  on  this  portion,  and 
is  called  the  occipital  protuberance  or  inion. 

TheJbasal  portion  bends  forward,  extending  far  enough  toward 
the  front  to  form  the  roof  of  the  throat  This  portion  presents  a 
large  opening  called  the  foramen  magnum  (or  great  foramen), 
which  transmits  the  spinal  cord.  At  the  sides  of  the  foramen 
magnum  are  two  smooth  prominences,  called  the  occipital  condyles, 
which  rest  upon  the  first  bone  of  the  spinal  column,  whereby  the 
nodding  movement  of  the  head  is  permitted. 


FIG.    13. — FRONTAL  BONE,  SHOWING 
THAT  IT  ORIGINATES  IN  HALVES. — 

(Morris.} 


22  ANATOMY   AND    PHYSIOLOGY 

The  inner  surface  of  this  bone  has  broad  grooves  for  the  transverse  sinuses 
(lateral  sinuses);  also  one  for  the  sagittal  sinus  (superior  longitudinal  sinus). 

Temporal  bones  (ossa  temporales). — Right  and  left;  situated 
at  the  sides  and  base  of  the  skull.  (See  Figs.  12  and  14.) 

Each  temporal  bone  consists  of  four  portions — the  squamous, 
the  mastoid,  the  petrous,  and  the  tympanic. 

The  squamous  portion  (squama  temporalis)  is  flat,  and  presents 
the  zygomatic  process  in  the  form  of  a  ridge  running  forward  in  front 
of  the  ear  to  the  cheek.  Below  the  beginning  of  this  process  is  the 
canal  leading  into  the  ear  and  called  the  external  auditory  meatus; 


FiG;  14. — PARIETAL,  TEMPORAL,  AND  SPHENOID  BONES;  POSTERIOR  ASPECT. 
i,  Body  of  sphenoid  bone;  2,  2,  greater  wing  and  squamous  portion  of  sphenoid 
bone;  3,  3,  parietal  bones;  4,  4,  mastoid  process  of  temporal  bones. — (Sappey.) 
The  occipital  bone  occupies  the  space  outlined  by  these  bones  posteriorly. 

just  in  front  of  that  is  the  mandibular  fossa,  where  the  lower  jaw- 
bone, or  mandible,  is  joined  to  the  temporal  bone  (Fig.  12). 

The  mastoid  pprflon  forms  the  prominence  ^behind  the  ear  and 
terminates  in  the  mastoid  process,  which  contains  a  number  of 
grnan  cavities,  tne  mastoid  cells.  They  all  communicate  with 
the  midoUe  ear,  and  mastoid  disease  may  therefore  ioiiow'  an 
iniection  of  the  middle  ear. 

The  inner  surface  of  this  portion  shows  the  sigmoid  groove  for  the  transverse 
sinus. 


PARIETAL   AND   ETHMOID   BONES  23 

The  petrous  portion  is  exceedingly  hard,  like  stone,  hence  its 
name.  A  slender  point  of  bone,  called  the  styloid  process,  is  seen 
on  its  lower  surface;  the  carotid  artery,  on  its  way  to  the  brain, 
passes  through  the  carotid  canal,  which  is  in  this  portion. 

The  petrous  bone  contains  the  greater  part  of  the  ear;  the 
internal  auditory  canal  for  the  auditory  nerve,  or  nerve  of  hear- 
ing, is  on  its  posterior  surface  (seen  within  the  skull). 

The  tympanic  portion  forms  the  greater  part  of  the  external  auditory 
meatus,  or  canal. 

Parietal  bones  (ossa  parietales). — Right  and  left,  situated  at 
the  top  and  sides  of  the  head,  and  so  named  because  they  form 
the  sides  or  walls  of  the  skull.  They  are.  flat  in  structure,  and 
nearly  square  in  shape;  the  four  borders  are  called  sagittal, 
squamous,  frontal,  and  occipital  (Figs.  12  and  14). 

At  the  extremities  of  the  borders  are  the  angles — the  frontal 
and  occipital  angles  above,  and  the  sphenoid  and  mastoid  angles 
below.  The  most  prominent  point  on  the  side  of  the  skull  is  near 
the  center  of  the  parietal  bone  and  is  called  the  parietal  eminence. 

On  the  inner  surface  of  this  bone  well-marked  grooves  are 
seen  for  the  middle  meningeal  artery,  and  depressions  for  the 
convolutions  of  the  brain. 

Ethmoid  bone  (os  ethmoidale). — Situated  between  the  orbits 
and,  therefore,  m  the  upper  part  of  the  nose.  (For  illustration 
see  pages  33,  34.) 

It  consists  principally  of  two  lateral  portions  formed  of  spongy 
bone,  and  containing  the  ethmoid  cells  or  sinuses.  These  portions 
are  called  ethmoid  labyrinths.  They  are  in  the  walls  of  the  nasal 
cavity  and  the  cells  open  into  it,  therefore  they  contain  air. 
The  labyrinths  are  attached  to  the  borders  of  the  horizontal 
plate,  which  is  situated  in  the  roof  of  the  nose  and  perforated  for 
the  passage  of  the  nerves  of  smell. 

The  upper  part  of  the  nasal  septum,  which  divides  the  nasal 
cavity  into  two  parts,  is  formed  by  the  vertical  plate  of  the  ethmoid, 
which  hangs  from  the  horizontal  plate,  and  is,  therefore,  between 
the  two  labyrinths  (Fig.  26). 

Two  of  the  turbinated  bones  (superior  and  middle)  project  from  the 
medial  surface  of  the  labyrinths  (Fig.  25).  (For  description  of  inferior 
turbinated  bone  see  page  26.) 


24  ANATOMY   AND   PHYSIOLOGY 

Sphenoid  bone  (os  sphenoidale) . — Immediately  behind  the 
ethmoid,  to  which  it  is  joined.  Its  shape  resembles  a  bat  with 
the  wings  spread  (Figs.  12  and  14).  It  consists  of  a  body,  wings, 
and  two  pterygoid  processes.  The  body  is  joined  to  the  ethmoid 
in  front,  and  to  the  occipital  behind.  It  is  hollow,  and  its  two 
cavities  (called  the  sphenoid  sinuses)  communicate  with  the  nose. 
The  wings,  two  pairs — greater  and  lesser — extend  outward  from 
the  body  at  about  the  level  of  the  orbits.  The  optic  foramen, 
for  the  optic  nerve,  is  in  the  lesser  wing. 

The  processes  extend  downward  from  the  body,  completing 
the  back  part  of  the  sides  of  the  nose. 

Note. — The  lateral  extremities  of  the  greater  wings  may  be  seen  at  the 
sides  of  the  skull,  between  the  frontal  and  temporal  bones;  the  sphenoid  is 
thus  wedged  in  behind  the  face,  between  it  and  the  other  cranial  bones.  (The 
name  sphenoid  signifies  wedge-tike.} 

ARTICULATIONS  OF  THE  CRANIUM 

The  joints  of  the  cranium  are  called  suturjgs.  Most  of  them 
are  formed  by  the  interlocking  of  irregular  edges  of  the  bones  held, 
firmly  together  by  fibrous  tissue  between  them.  Sometimes  the 
edges  resemble  saw-teeth  in  form,  and  then  the  suture  is  dentated 
or  serrated.  Sometimes  the  edges  are  smooth  and  overlap  each 
other,  and  sometimes  one  fits  between  two  others;  but  they  are 
always  immovable.  (For  illustration,  see  Fig.  12.) 

The  sutures  which  are  most  important  for  the  nurse  to  recog- 
nize are  those  formed  with  three  borders  of  the  parietal  bones. 
The  two  sagittal  (or  superior)  borders,  uniting  with  each  other, 
form  the  sagittal  suture;  the  frontal  borders,  uniting  with  the 
frontal  bone,  form  the  coronal  suture,  while  the  occipital  borders, 
uniting  with  the  occipital  bone,  form  the  lambdoid  suture. 

BONES  OF  THE  FACE,  14 

Nasal 2  Palate 2 

Lacrimal 2  Inferior  turbinated. . .    2 

Zygomatic 2  Vomer i 

Superior  maxillary ...    2  Inferior  maxillary,  or 

united,  form  the  maxilla.  mandible i 

Nasal  bones  (os  nasale,  sing.). — Right  and  left.  (Fig.  12.) 
They  are  flat  in  structure  and  form  the  bridge  of  the  nose,  being 


THE   MAXILLA 


joined  to  each  other  in  the  median  line  of  the  face  and  to  the  frontal 
bone  above. 

Lacrimal  bones  (os  lacrimale,  sing.). — Right  and  left;  small 
and  thin,  situated  in  the  walls  of  the  orbits,  just  under  the  ex- 
tremity of  the  supraorbital  margin  (Figs.  1 2  and  24).  In  this  bone 
is  the  beginning  of  the  canal  in  which  the  lacrimal  duct  runs  con- 
veying the  tears  into  the  nose,  thus  preventing  them  from  over- 
flowing the  eyelids  and  running  down  the  cheek. 

Zygomatic  bones  (os  zygomaticum,  sing.). — Forming  the  promi- 
nences of  the  cheek  (Fig.  12).  They  are  especially  noticeable 
in  certain  races,  as  the  Chinese,  for  example,  who  have  high 
" cheek  bones." 

Maxilla  (or  upper  jaw-bone). — Situated  in  the  front  of  the 
face,  and  composed  of  the  two  superior  maxillary  bones  joined 


Infraorbital  foramen 

Canine  fossa 

Nasal  spine 

Incisive  fossa 

Canine  eminence 


Articulates  with  zygo- 

matic  bone 
Posterior  dental  canals 


Tuberosity 


FIG.  15. — THE  MAXILLA. — (Morris.} 

together  below  the  nostrils.  It  supports  the  cheeks,  helps  to  form 
the  nose  and  also  the  floor  of  the  orbits.  It  consists  of  a  body  and 
several  processes. 

The  body  is  hollow,  the  space  being  called  the  maxillary  sinus 
or  antrum  of  Highmore  which  opens  into  the  side  of  the  nasal 
cavity.  In  the  lower  border  of  the  body  the  teeth  are  imbedded, 
the  sockets  of  the  large  teeth  being  in  the  floor  of  the  antrum, 
which  explains  how  a  diseased  tooth  may  lead  to  antrum  trouble. 

The  foramen  on  the  surface  of  the  body  just  below  the  orbit  is  called  the 
infraorbital  foramen.  It  is  on  a  line  with  the  supraorbital  foramen  of  the 
frontal  bone  already  mentioned. 


26 


ANATOMY  AND   PHYSIOLOGY 


Processes. — The  frontal  process  extends  upward  along  the 
side  of  the  nasal  bone  to  join  the  frontal.  The  palate  process 
is  in  the  roof  of  the  mouth,  the  bony  part  of  the  roof  being  called 
the  hard  palate.  The  alveolar  process  (or  alveolus)  is  the  thick 
border  of  bone  in  which  the  upper  teeth  are  fixed.  This  process 
is  very  spongy  and  is  sometimes  broken  in  extracting  a  tooth. 
The  zygomatic  process  joins  the  zygomatic  bone  to  form  the 
prominence  of  the  cheek. 


I  Foramina  and  in- 
I      cisive  suture 


Palate  process 


1  Palatine  foramina 
J   in  a  palate  bone 


FIG.  16. — THE  HARD  PALATE,  OR  ROOF  OF  THE  MOUTH. — (Morris.} 

Palate  bones  (os  palatinum,  sing.). — Right  and  left;  shaped  like 
the  capital  letter  L,  and  placed  behind  the  maxilla.  The  upright 
portion  is  in  the  side  of  the  nose  at  the  back;  the  horizontal 
portion  lies  in  the  floor  of  the  nose,  being  at  the  same  time  in  the 
roof  of  the  mouth,  and  thus  completing  the  hard  palate  (Fig.  2 1) . 

Inferior  turbinated  bones  (concha  nasalis  inferior,  sing.). — 
Right  and  left;  situated  in  the  right  and  left  walls  of  the  nasal 
cavity  below  the  superior  and  middle  turbinated  bones  which 
belong  to  the  ethmoid  (Fig.  25).  Each  is  composed  of  a  thin  plate 
of  spongy  tissue,  having  one  edge  rolled  under  like  a  shell  (concha); 
they  extend  from  front  to  back  on  the  lateral  wall  of  the  cavity. 

Clinical  note. — Hypertrophy  (or  overgrowth)  of  the  inferior 
turbinated  bone  is  a  frequent  cause  of  obstruction  to  proper 
breathing. 

Vomer. — A  thin  bone  resembling  a  plowshare  in  shape,  joined 
.  above  with  the  vertical  plate  of  the  ethmoid,  and  below  with  the 


THE   MANDIBLE 


maxilla,  thus  forming  the  lower  part  of  the  septum  of  the  nose.  It 
is  this  part  of  the  septum  which  is  sometimes  bent  to  one  side,  or 
"deflected,"  and  it  often  presents  a  "spur"  on  one  of  its  surfaces. 
(The  vertical  plate  of  the  ethmoid  and  the  vomer  together  form  the 
bony  septum,  Fig.  26.) 


Articulates  with 
ethmoid 


Groove  for  nerve 


Articulates  with 
hard  palate 


Ala 

Posterior  border 


FIG.  17. — THE  VOMER. — (Morris.} 


Mandible  (inferior  maxillary,  or  lower  jaw-bone,  mandibula). — 
The  only  movable  bone  in  the  skull.  It  consists  of  a  body  having 
on  either  side  a  ramus  (or  branch)  which  is  attached  bv  ligaments^ 
to  the  temporal  bone. 

The  body  is  the  lower  portion,  shaped  much  like  a  horseshoe 
with  a  thickened  border  (the  alveolus]  which  bears  the  lower 
teeth. 


FIG.  18. — THE  MANDIBLE. 

i,  Body  of  bone;  2,  ramus;  3,  symphysis;  4,  incisive  fossa;  5,  mental  foramen;  7, 
depression  for  passage  of  facial  artery;  8,  angle  of  jaw;  10,  coronoid  process;  n, 
condyle;  12,  sigmoid  notch;  13,  alveolar  border;  a,  incisors;  b,  bicuspids;  c,  canines; 
m,  molars. — (Sappey.) 

On  each  side  is  an  opening  called  the  mental  foramen,  which  is  in  a  line 
with  the  infraorbital  and  supraorbital  foramina,  already  mentioned. 

Each  of  these  three  openings  transmits  an  important  nerve,  artery,  and 
vein,  bearing  the  same  name  as  the  foramen.  See  Surgical  note,  p.  308. 

The  ramus  extends  upward  from  the  body,  and  ends  in  two 
processes,  one  of  which  is  the  condyle;  it  is  this  condyle  which 
articulates  with  the  temporal  bone  to  form  the  temporo-maxillary 
joint. 


28  ANATOMY   AND    PHYSIOLOGY 

Clinical  note. — Dislocation  of  this  joint  easily  occurs  if  the 
mouth  is  opened  too  widely. 

The  angle  of  the  jaw  or  mandible,  is  the  posterior  extremity  of  the  lower 
border.  The  prominence  of  the  angle  differs  in  different  people  and  at 
different  ages. 

ARTICULATIONS  OF  THE  FACE 

The  bones  of  the  face  are  all  irregular,  and  many  of  them  are 
very  frail.  They  are  fixed  by  sutures  with  one  exception — that 
of  the  mandible  which  moves  freely.  (For  description  of  a 
movable  joint,  see  page  17.) 


THE  MANDIBULAR  JOINT 

The  mandibular  joint  is  a  hinge-joint^  and  the  only  movable 
joint  in  the  skull.  The  action  may  be  felt  in  front  of  the  ear. 

The  bony  surfaces  are  the  condyle  of  the  mandible  and  the 
mandibular  fossa  of  the  temporal  bone.  They  are  covered  with 


Capsule 


FIG.  19. — MANDIBULAR  JOINT. — (After  Morris.) 

cartilage  and  connected  by  ligaments  forming  a  capsule,  which  is 
sufficiently  loose  to  allow  the  condyle  to  glide  freely  in  the  fossa, 
back  and  forth  or  sidewise,  as  in  opening  and  closing  the  mouth 
and  masticating  the  food. 

Surgical  notes. — If    the   mouth   be    suddenly    opened    very 
widely,  as  in  hearty  laughing,  dislocation  easily  results — that  is, 


THE   CRANIUM  29 

the  condyles  glide  too  far  forward  and  slip  in  front  of  the  fossa, 
making  it  impossible  to  close  the  mouth.  To  correct  this  con- 
dition (or  " reduce  the  dislocation")  press  the  jaw  forcibly  down- 
ward and  backward  with  the  thumbs  placed  upon  the  molar  teeth. 
(First  wrap  the  thumbs  with  a  napkin  to  protect  them,  as  the 
mouth  will  close  suddenly.) 


POINTS  OF  INTEREST  IN  CONNECTION  WITH  THE 
SKULL  AS  A  WHOLE 

THE  CRANIUM 

The  cranium  is  a  firm,  strong  case  for  the  brain,  composed 
largely  of  flat  bones,  the  layers  of  these  flat  bones  being  called  the 


B REG MA 


ANTERIOR    NASA 
SPINE 


PROSTHIO 


GNATHI 


BELION 


MBDA 


FIG.  20. — THE  VERTEX  AND  SIDE  OF  THE  SKULL. — (Gerrish.) 

tables  of  the  skull.  The  innermost  table  is  very  brittle  and  may  be 
fractured  by  a  blow  which  does  not  break  the  outer  one,  and 
owing  to  this  brittleness  it  is  called  the  vitreous,  or  glassy  layer. 

Observing  the  illustrations,  or  better,  with  the  skull  in  the 
hand,  the  student  may  trace  the  frontal,  two  parietal,  and 
occipital  bones  forming  the  vault  of  the  skull,  or  the  vertex;  and  at 


30  ANATOMY   AND    PHYSIOLOGY 

the  sides  the  squamous  and  mastoid  portions  of  the   temporal 
bones  and  the  tip  of  the  great  wing  of  the  sphenoid. 

Turning  the  skull  upside  down,  observe  the  base.  In  the 
median  line  at  the  back  is  the  basal  part  of  the  occipital  bone, 
with  the  foramen  magnum  and  the  condyles  on  either  side  of  it. 
In  front  of  that  are  the  body  and  processes  of  the  sphenoid,  and 
the  roof  of  the  mouth  (or  hard  palate)  bounded  by  the  upper 
teeth.  Tracing  forward  from  the  lateral  part  of  the  occipital 


FIG.  21. — BASE  OF  SKULL. 

i,  2,  3,  Foramina  and  sutures  in  hard  palate;  4,  post-nasal  spine;  5,  nasal  septum; 
6,  7,  8,  Q,  10,  n,  12,  pterygoid  processes,  and  markings  on  sphenoid  bone;  13,  zygo- 
matic  arch;  14,  spheno-occipital  suture;  15,  16,  17,  18,  19,  20,  markings  on  tem- 
poral bone;  21,  21,  condyles  of  occipital  bone;  22,  basal  portion  of  occipital  bone; 
23,  foramen  magnum;  24,  25,  crest  and  lines  of  occipital  bone. — (Sappey.) 

bone  is  the  petrous  portion  of  the  temporal,  with  its  sharp  styloid 
process  and  round  opening  of  the  carotid  canal;  and  in  front  of  the 
temporal  is  the  great  wing  of  the  sphenoid.  The  ethmoid  may  be 
seen  through  the  posterior  nares  where  the  turbinated  bones 
(better,  shell-bones)  are  all  visible. 

Numerous  openings  or  foramina  pierce  the  base  of  the  skull, 


THE    FACE 


for  vessels  and  nerves.  The  jugular  foramen  is  just  back  of  the 
carotid  canal;  through  it  the  jugular  vein  leaves  the  skull  to  pass 
downward  in  the  neck.  The  interior  surfaces  of  all  cranial  bones 
show  depressions  for  the  convolutions  of  the  brain. 


THE  FACE 

(See  Figs.  20,  24.) 

Beginning  with  the  forehead,  note  the  two  frontal  eminences, 
and  below  these  the  superciliary  arches  with  the  glabella  between 
them.  Still  lower,  the  supraorbital  arches,  with  the  nasal  notch 
between  them,  to  which  the  nasal  bones  are  attached.  Observe 


FIG.  2 2.— SKULL  OF  NEW-BORN  CHILD, 
SHOWING  FRONTAL  FONTANELLE. — 
(Edgar.} 


FIG.  2  3. -^OCCIPITAL  FONTANELLE. 
Both  cuts  show  moulding  of  the  head. — 
(Edgar.} 


the  lacrimal  canal  at  the  medial  side  of  the  orbit  leading  to  the 
nasal  cavity.  Below  the  orbit,  locate  the  infraorbital  foramen  on 
the  surface  of  the  maxilla  and  the  mental  foramen  on  the  body  of 
the  mandible. 

Remember  that  these  three  foramina  transmit  three  very  sensitive  nerves, 
as  follows: — The  supraorbital  nerve  for  the  forehead,  the  infraorbital  nerve  for 
the  cheek,  and  the  mental  nerve  for  the  lower  lip  and  chin.  (Blood-vessels 
bearing  the  same  names  accompany  these  nerves.) 


The  prominences  at  the  sides  of  the  cheeks  are  made  by  the 
zygomatic   bones.     The  openings   of   the  nasal   cavity  are   the 


anterior  nares,  within  which  may  be  seen  the  septum,  and  the 
middle  and  inferior  turbinated  bones  (shell  bones). 


32  ANATOMY  AND  PHYSIOLOGY 

THE  SKULL  AT  BIRTH 

The  bones  are  only  partially  developed,  a  considerable  space 
between  them  being  occupied  by  membrane  (in  some  places, 
cartilage),  and  the  frontal,  bone  is  in  two  pieces. 

Fontanelles. — The  parietal  and  frontal  bones  are  incomplete 
at  the  angles  where  their  sutures  meet,  leaving  a  diamond-shaped 
space  above  the  forehead  where  there  is  membrane  only,  and  which 
is  called  the  anterior  or  frontal  fontanelle.  The  parietal  and 
occipital  bones  also  are  lacking  where  their  sutures  meet,  leaving 
a  triangular  soft  spot  called  the  posterior  or  occipital  fontanelle, 
which  is  much  smaller.  These  fontanelles  are  closed  as  the  bones 
develop;  the  occipital  in  a  few  months,  the  frontal  before  the  end  of 
the  second  year. 


Superciliary 
ridge 

Glabella 


FIG.  24. — THE  ORBIT. — (After  Morris.) 

Obstetric  note. — Owing  to  the  fact  that  the  bones  are  not 
firmly  jointed,  they  can  be  made  to  overlap  and  thus  adapt  the 
shape  of  the  Child's  head  to  the  passage  which  it  must  traverse 
during  birth.  This  is  called  the  moulding  of  the  head  (Figs.  22 
and  23). 


FOSS.E  OF  THE  SKULL 

The  four  large  fossae  of  the  exterior  of  the  skull  are  the  tem- 
poral, infratemporal,  orbital,  and  nasal. 

The  temporal  fossa   (fossa  temporalis). — The  thinnest  part 


FOSS.E   OF    SKULL 


33 


of  the  skull  (Fig.  20).  It  is  bounded  by  the  temporal  ridge  and 
the  zygomatic  arch,  occupied  by  the  temporal  muscle,  and  covered 
by  a  strong  membrane,  called  the  temporal  fascia,  through  which 
the  motion  of  the  muscle  may  be  felt. 

Infratemporal  (or  zygomatic)  fossa. — At  the  side  of  the  skull 
below  the  temporal  fossa,  from  which  it  is  separated  by  the  zygo- 
matic arch  (Fig.  20).  It  is  covered  by  the  ramus  of  the  mandible, 
and  occupied  by  two  of  the  muscles  of  mastication,  and  also  by  a 
number  of  important  arteries,  veins,  and  nerves. 


Concha  superior 


Sphenoidal  sinus 


Superior! 
meatus  I 


Concha 
media 


Middle  meatus 

Palate  bone 
Inferior  meatus 


Middle 
meatus 


Concha 
inferior 
Probe  emerg- 
ing from 
nasal  canal 

Ant.  pala- 
tine canal 


FIG.  25. — LATERAL  WALL  OF  NASAL  FOSSA  OR  CAVITY. — (Morris.} 

Orbital  fossa  (or  orbit). — containing  the  eye.  It  is  shaped 
like  a  pyramid,  the  apex  being  at  the  back  of  the  fossa.  The 
large  opening  on  the  face  is  bounded  by  the  margins  of  the  orbit, 
having  the  frontal  bone  above,  the  maxilla  below,  and  the  zygo- 
matic bone  on  the  lateral  side. 

The  orbital  plate  of  the  frontal  bone  is  in  the  roof  of  the  orbit,  and_the 
3 


34 


ANATOMY   AND   PHYSIOLOGY 


orbital  plate  of  the  maxilla  in  the  floor.     The  lacrimal  and  ethmoid  bones  are 
in  the  medial  wall;  the  sphenoid  and  zygomatic  bones  in  the  lateral  wall. 

The  lacrimal  canal  begins  in  the  lacrimal  bone  and  runs  down 
into  the  nose.  The  optic  foramen,  for  the  optic  nerve,  is  at  the 
apex  of  the  fossa. 

Nasal  fossa. — Roof  formed  by  nasal  and  ethmoid  bones;  floor 
by  maxillary  and  palate  bones;  lateral  watt  by  nasal,  ethmoid, 


FIG.  26.— THE  BONY  SEPTUM. 
Body  of  sphenoid  immediately  be- 
hind it. — (Morris.) 


FIG.  27. — HYOID  BONE,  ANTERIOR 

ASPECT. 

i,  i,  Anterior  or  convex  surface  of 
body;  2,  2,  greater  cornua;  3,  3,  junc- 
tion of  greater  cornua  with  body;  4, 
lesser  cornua. — (Sappey.) 


maxillary,  and   palate   bones;  septum   by   ethmoid    and  vomer 
(Fig.  26). 

The  openings  on  the  face,  or  anterior  nares,  are  bounded  by  the 
maxillary  and  nasal  bones,  and  separated  by  the  vomer.  The 
openings  into  the  throat  or  posterior  nares  are  bounded  by  the 
sphenoid  and  palate  bones,  and  separated  by  the  vomer.  Turbi- 
nated  bones  are  seen  on  the  lateral  walls  of  the  fossae. 

Each  nasal  fossa  communicates  with  four  sinuses:  the  sphenoid,  ethmoid, 
frontal,  and  maxillary.  The  sphenoid  sinus  opens  into  the  upper  and  back 
part;  the  ethmoid,  frontal,  and  maxillary  (or  antrum  of  Highmore)  open  at  the 
side,  lower  down.  The  lacrimal  canal  also  opens  at  the  side  near  the  floor. 

The  nasal  fossae  are  lined  with  mucous  membrane  (the 
Schneiderian  membrane)  which  is  continued  into  all  of  the  sinuses 
and  the  pharynx. 

Clinical  note. — Inflammation  of  this  membrane  may  extend 


THE   TEETH  35 

into  any  of  the  sinuses,  causing  sinusitis.  If  this  occurs  in  the 
frontal  region,  a  dull  pain  is  felt  over  the  eyes;  if  in  the  ethmoid 
region,  a  pain  at  the  side  of  the  nose  and  a  change  in  the  sound  of 
the  voice  (nasal  tone)  are  noted.  The  inflammation  frequently 
extends  into  the  antrum  of  Highmore. 

The  sense  of  smell  resides  in  the  upper  part  of  the  nose,  the 
olfactory  nerves  coming  down  through  the  sieve-like  plate  of  the 
ethmoid  bone  in  the  roof  of  the  fossa. 

BONES  OF  THE  NECK 

Hyoid  (os  hy aides). 
Seven  cervical  vertebrae. 

The  hyoid  bone,  or  os  hyoides. — Shaped  like  the  letter  U, 
situated  in  front  of  neck,  about  on  a  level  with  the  chin,  and  sus- 
pended by  ligaments  and  muscles  from  the  styloid  process  of  the 
temporal  bone.  The  hyoid  is  not  articulated  to  any  other  bone. 
It  consists  of  a  body  and  four  cornua  (or  horns),  and  is  designed 
to  give  attachment  to  the  muscles  of  the  tongue,  and  to  others 
which  connect  it  to  the  mandible  above  and  sternum  and  clavicle 
below. 

Seven  cervical  vertebrae. — The  seven  cervical  vertebrae  and 
their  articulations  will  be  described  with  the  spinal  column. 

THE  TEETH 

A  tooth  is  composed  of  dentine  or  tooth-bone,  and  consists 
briefly  of  a  crown,  a.  neck,  and  a  root. 

Crown  _____  a|_ 

.  _,_        -Root 

Cusp- 
Neck-  

HI  cav"y  H 

_     .  'Neck 

i  /   ii  mi 

•Qngulum. 
"Crown 

FIG.  28. — A  MOLAR  TOOTH  IN  SECTION  AND  A  CANINE  TOOTH. — (Morris.) 

The  crown  is  the  exposed  portion  and  is  covered  with  hard 
white  enamel.  The  root  (connected  with  the  crown  by  the  neck) 
is  concealed  in  the  socket  of  the  jaw  and  is  covered  with  cement. 
The  shape  of  the  tooth  varies  from  that  of  the  flat  incisor  or  cutting 
tooth,  to  the  broad  one  for  crushing  and  grinding. 


36  ANATOMY   AND   PHYSIOLOGY 

The  incisors  are  the  front  teeth,  f^nr  in  number  in  each  jaw. 
They  are  used  for  biting  and  nittinfr  the  fond. 

The  cuspids  (pointed)  or  canine  teeth  are  situated  next  to  the 
incisors;  they  also  bite  and  masticate. 

The  bicuspids  (two-pointed)  or  pre-molars,  and  the  molars  are 
for  purposes  of  mastication. 

The  shapes  of  all  are  shown  in  the  illustrations. 

The  teeth  are  hollow  and  contain  tooth-pulp.  This  consists  of 
a  delicate  meshwork  of  vessels  and  nerves  entering  at  the  point  of 
the  root,  wrapped  in  connective  tissue  and  filling  the  pulp  cavity. 

The  upper  teeth  are  imbedded  in  the  alveolus  of  the  maxilla,  or 
upper  jaw;  the  lower  teeth  in  the  alveolus  of  the  mandible,  or  lower 
jaw. 

Dentition :  the  Eruption  of  the  Teeth 

The  teeth  make  their  appearance  in  two  sets,  called  temporary 
and  permanent. 


FIG.  29. — THE  TEMPORARY  TEETH. 
The  rudiments  of  the  permanent  teeth  are  seen  enclosed  in  the  bones. — (Gorgas.) 

The  temporary  teeth  are  twenty  in  number:  their  eruption  or 
"cutting^  usually  begins  at  about  the  seventh  month  and  proceeds 
in  following  order: 

Two  lower  central  incisors at    7  months. 

Two  upper  central  incisors at    8  to  10  months. 

Two  upper  lateral  incisors at    9  to  1 2  months. 


TEMPORARY   TEETH 


37 


Two  lower  lateral  incisors.* at  12  to  15  months. 

Four  first  molars,  i  right,  i  left  in  each  jaw....  at  12  to  15  months. 

Four  canines,  i  right,  i  left  in  each  jaw at  16  to  22  months. 

Four  second  molars,  i  right,  i  left  in  each  jaw.,  at  24  to  30  months. 

Twenty  teeth  in  the  temporary  set  at  two  and  one-half  years  of  age. 

Thus,  at  one  year  of  age  the  average  child  will  have  six  teeth; 
at  two  years,  sixteen;  and  the  full  number  before  it  is  three  years 
old.  Many  exceptions  occur,  for  example:  the  dentition  of  arti- 
ficially fed  children  may  be  delayed;  and  it  is  oftenest  late  in 
children  affected  by  rachitis  or  "  rickets." 

The  upper  canines  are  known  in  the  nursery  as  "eye-teeth";  the  lower 
canines  as  "stomach  teeth." 

Clinical  points.- — "Teething"  or  " cutting"  of  the  temporary 
set  occurs  while  the  digestive  tract  is  still  in  process  of  develop- 
ment and  very  easily  disturbed;  therefore  special  care  should  be 


Incisors 


Canine 


Premolar 


Molars 


Wisdom  tooth 


Upper 
or  max- 
illary 
teeth 


P  V 


FIG.  30. — THE  TEETH  OF  AN  ADULT. — (Morris1  Anatomy.} 

given  to  the  child's  diet  both  as  to  quality  and  quantity.  Like- 
wise, the  always  delicate  nervous  system  is  at  this  time  most  easily 
irritated  and  excitement  and  fatigue  should  be  avoided.  These 
two  points  are  equally  important. 

Meanwhile  the  permanent  teeth  are  forming  (Fig.  30).  They 
gradually  push  toward  the  surface,  cutting  off  the  blood  supply  to 
the  temporary  teeth  which  become  loose  and  fall  out. 


38  ANATOMY  AND   PHYSIOLOGY 

The  permanent  teeth  are  thirty-two  in  number.  At  the  age 
of  six  years  the  first  permanent  molar  ("six-year  molar")  should 
appear;  the  others  follow  in  order  somewhat  like  the  following: 

Four  first  molars,  i  right,  i  left,  in  each  jaw. ...  at  6  years. 

Eight  incisors,  2  central,  2  lateral,  in  each  jaw . .  at  7  to    8  years. 

Eight  bicuspids,  2  right,  2  left,  in  each  jaw at  8  to  10  years. 

Four  canines,  i  right,  i  left,  in  each  jaw at  12  to  14  years. 

Four  second  molars,  i  right,  i  left,  in  each  jaw. .  at  12  to  15  years. 

Four  third  molars,  i  right,  i  left,  in  each  jaw... .  at  17  to  25  years. 
(The  third  molars  are  called  "wisdom  teeth.") 

Thirty-two  teeth  in  the  permanent  set  at  twenty-five  years  of  age. 

Clinical  notes. — Caries,  or  decay  of  teeth,  is  due  to  bacterial 
action.  This  is  favored  by  the  accumulation  of  particles  of  food, 
the  warmth  and  moisture  of  the  mouth  furnishing  perfect  conditions 
for  the  development  of  bacteria.  Careful  cleansing  with  brush  or 
dental  floss,  or  both,  will  prevent  this  and  thus  aid  in  preserving 
the  teeth.  Care  is  important  in  the  use  of  brush  or  floss  or 
toothpick,  not  only  that  the  removal  of  injurious  particles  may  be 
well  done  but  in  order  to  avoid  wounding  the  mucous  membrane 
which  covers  the  gums,  thus  exposing  them  to  bacterial  invasion. 

Recession  of  the  Gums. — Any  irritation  (as  by  bacteria)  of  the 
gums  may  be  followed  by  their  recession,  which  exposes  the  dentine 
where  it  is  not  protected  by  enamel. 

Sudden  changes  of  temperature,  as  from  hot  to  cold  liquids,  is 
injurious  to  the  enamel.  Acids,  as  ordinarily  taken  in  food,  have 
no  special  action  upon  the  teeth,  but  sweets  may  do  harm  by 
their  fermentation  in  a  mouth  where  teeth  are  not  kept  clean. 

The  sockets  of  the  teeth  are  lined  wi'th  periosteum  (dental 
periosteum).  It  is  reflected  at  the  bottom  of  the  socket  to  the  root 
of  the  tooth  and  covers  the  cement;  this  portion  is  called  the 
peri-cemental  membrane  (or  periosteum). 

Bacterial  invasion  of  the  gums  may  extend  beneath  the  periosteum,  caus- 
ing a  chronic  inflammation  with  suppuration,  called  pyorrhea  alveolaris. 
Often  the  condition  is  painful,  mastication  is  difficult  and  the  teeth  loosen  and 
almost  fall  out  of  themselves. 


CHAPTER  III 

BONES  AKD  ARTICULATIONS  OF  THE 
SPINAL  COLUMN  AND  TRUNK 

The  bones  of  the  spinal  column  are 
twenty-six  in  number.  They  are  irregular 
and  are  arranged  as  follows,  from  above 
downward: 


24  separate  vertebrae 


i  sacrum, 
i  coccyx. 


7  cervical  in  the  neck. 

12  thoracic  in  the  back. 

5  lumbar  in  the  loins. 

in  the  pelvis. 


A  vertebra  consists  of  a _body  and  an 
arch,  joined,  together  to  form  a  ring  of 
Done  with  a  space  enclosed  called  the 
vertebraTforamen ,  which  is  occupied  by  the 
spinal  cord.  Trie  bodies  are  composed  of 
spongy  bone,  placed  one  above  the  other 
and  held  together  by  discs  of  fibrocartilage 
between  them.  In  this  way  the  solid  and 
flexible  portion  of  the  spine  is  constructed. 

The  arch  consists  of  two  roots  next  to  the 
body,  antt  two  larkiriti  which  meet  at  the 
l)ack. '  There  are  seven  processes  on  the 
arch  of  each  vertebra — tour  articular  (two 
to  form  joints  with  the  bone  above,  two 
for  the  bone  below);  two  transverse  (pro- 
j'ecting  from  the  sides),  and  one  spinou^ 
which  projects  backward.  The  row  of 
spinous  processes  is  felt  by  passing  the  finger 
down  the  back  in  the  median  line;  that  of 
the  seventh  vertebra  is  easily  seen,  and 
this  bone  is  called  the  vertebra  prominent. 

39 


FIG.   31. — VERTEBRAL 
COLUMN,  LATERAL  ASPECT. 

1-7,  Cervical  vertebrae; 
8-19,  dorsal  vertebras;  20- 
24,  lumbar  vertebrae;  A,  A, 
spinous  processes;  B,  B, 
articular  facets  of  trans- 
verse processes  of  first  ten 
dorsal  vertebrae;  C,  auricu- 
lar surface  of  sacrum;  D, 
D,  foramina  in  transverse 
processes  of  cervical  verte- 
brae— (Sappey.) 


4O  ANATOMY   AND   PHYSIOLOGY 

POINTS  or  SPECIAL  INTEREST 

The  cervical  vertebrae  present  a  foramen  at  the  base  of  the 
transverse  process,  the  transverse  foramen,  through  which  an  artery 
runs  to  the  brain,  entering  the  skull  through  the  foramen  mag- 
num. (There  are  no  transverse  foramina  in  the  dorsal  or  lumbar 
regions.) 

Their  spinous  processes  are  cleft  or  bifid. 


Transverse  foramen 
Transverse  process 

Articular  process 


Lamina 


Spinous  process 


Pedicle 


FIG.  32. — CERVICAL  VERTEBRA,  SHOWING  BIFID  SPINOUS  PROCESS. — (Morris.) 


FIG.  33. — ATLAS,  SUPERIOR  SURFACE. 
i,  Tubercle  of  anterior  arch;  2, 
articular  facet  for  odontoid  process 
of  axis;  3,  posterior  arch  and  posterior 
tubercle;  4,  groove  for  vertebral  artery 
and  first  cervical  nerve;  5,  transverse 
process1;- 6,  transverse  foramen;  7, 
superior  articular  process;  8,  tubercle 
for  attachment  of  transverse  ligament. 
—(Sappey.) 


FIG:  34. — Axis  POSTERO- 

SUPERIOR  VIEW. 
i,  Posterior  surface  of 
body;  2,  odontoid  proc- 
ess; 3»  3>  superior  articu- 
lar processes;  4,  4,  inferior 
articular  processes;  5, 

5,  transverse    processes; 

6,  spinous  process. 
—(Sappey.) 


The  first  is  called  the  atlas.  It  is  a  mere  ring  but  has  the  usual  number  of 
processes  (Fig.  33).  The  atlas  is  so  named  because  it  bears  the  weight  of  the 
skull  (as  Atlas,  the  fabled  giant,  bore  the  globe  upon  his  shoulders). 

The  second  is  the  axis.  A  strong  process  projects  upward  from  its  body 
forming  a  pivot  for  thlF  ring-like  atlas  to  revolve  around.  The  pivot  is  called 


THE    SACRUM  4! 

the  tooth  (or  odontoid  process)  and  is  held  in  its  place  in  the  front  part  of 
the  ring  of  the  atlas  (Fig.  33)  by  a  strong  ligament,  which  prevents  it  from 
pressing  upon  the  spinal  cord. 

The  thoracic  vertebras  are  peculiar,  in  that  their  bodies  present 
marks  for  the  heads  of  ribs;  also,  they  have  long  transverse  and 
>inous  processes. 


FIG.  35. — A  THORACIC  VERTEBRA,  SHOWING  MARKS  FOR  HEAD  OF  RIB. — (Morris.} 

Thejumbar  vertebrae  are  the  largest  and  strongest  in  'the 
column,  the  bodies  being  conspicuously  thicker  than  in  the  other 
regions,  especially  in  the  case  of  the  fifth. 

There  are  various  other  modifications  of  bones  in  the  three  regions — 
cervical,  dorsal,  and  lumbar — which  need  not  be  mentioned  here. 


FIG.  36. — A  LUMBAR  VERTEBRA  IN  SECTION  TO  SHOW  THE  PRESSURE  CURVES. — 

(Morris.) 

Sacrum. — An  irregular  bone  formed  by  the  consolidation  of 
five  incomplete  vertebras,  and  joined  to  the  last  lumbar.  Its 
genelal  bliape  lii  that  oi  a  curved  wedge;  it  is  placed  with  the 
base  upward,  and  the  concavity  forward,  forming  the  "hollow  of 
the  sacrum"  A  canal  extends  from  the  base  to  the  apex,  called 
the  sacral  canal,  which  is  a  continuation  of  the  spinal  (or  neural) 
canal. 

There  are  two  sets  of  short  canals,  running  from  front  to  back 
through  the  sacrum.  Seen  from  the  front  they  present  the  an- 


ANATOMY   AND   PHYSIOLOGY 


terior  sacral  foramina;  seen  from  the  back,  the  posterior  sacral 
foramina  (both  are  for  the  passage  of  nerves)  .  The  angle  formed 
by  the  sacrum  and  the  fifth  lumbar  vertebra  projects  sharply 
forward  and  is  called  the  promontory. 

Coccyx.  —  The  terminal  bone  of  the  spinal  column,  and  formed 
_of  four  very  rudimentary  vertebrae^    The  base  is  Joined  to  the 


sacrum  ;  the  apex  is  directed  downward  and  forward.^ 


FIG.  37. — SACRUM,  ANTERIOR  ASPECT. 
i,  i,  i,  i,  Bodies  of  sacral  vertebrae  with  trans- 
verse lines  of  union;  2,2,2,2,  anterior  sacral  foram- 
ina; 3,  base;  4,  auricular  surface  of  lateral  aspect; 
5,  its  inferior  portion;  6,  articular  surface  of  base; 
7,  notch  for  formation  of  last  lumbar  intervertebral 
foramen;  8,  superior  articular  process  of  first  sacral 
vertebra;  9,  apex  of  sacrum;  10,  cornu;  n,  notch 
for  transmission  of  fifth  sacral  nerve. — (Sappcy.) 


FIG.  38. — COCCYX,    ANTE- 
RIOR ASPECT. 
i,  Base;  2,  2,  cornua;  3, 
second    coccygeal    vertebra; 

4,  third  coccygeal  vertebra; 

5,  fourth  coccygeal  vertebra; 

6,  fifth  coccygeal  vertebra. — 
(Sappey.) 


THE  ARTICULATIONS  OF  THE  SPINAL  COLUMN 


The  bodies  of  the  vertebrae  are  connected  by  discs  of  fibro- 
cartilage  which  are  placed  between  them.  They  serve  not  only 
lu  luiiiiLil  the  vertebras  but  to  give  flexibility  to  the  column,  so 
that  it  may  bend  in  any  direction,  and  they  also  make  it  elastic. 
The  bodies  are  further  connected  by  fibrous  bands  on  their  anterior 
and  posterior  surfaces.  (Slightly  movable  or  yielding  joints.) 

The  arches  are  connected  by  broad  thin  ligaments  between  the 
laminae,  thus  completing  the  spinal  or  neural  canal,  which  conrtains 
the  spinal  cord.  (These  ligaments  are  an  exception  to  the  rule, 
in  that  they  are  elastic;  they  are  called  the  ligamenta  flava.)  The 
articular  processes  are  covered  with  cartilage  and  enclosed  by 
capsules  which  are  lined  with  synovial  membrane,  forming  true 
movable  joints.  These  are  gliding  joints.  (Arthrodia.) 

The  only  independent  movements  of  the  head  are  provided  for 


THE   SPINAL   COLUMN 


43 


hvthe  arrangement  of  the  atlas  and  axis.  The  nip-like  arti'mlar 
processes  of  the  atlas  receive  the  condyles  of  the  occipital  hone  fo, 
allow  the  nodding  motion  of  the  head.  The  occipital  bone  is  held 
to  the  atlas  by  ligaments,  and  rotation  of  the  atlas  around  the  tooth 
of  .the  axis  turns  the  head  also,  from  side  to  side. 

The  ligamentum  nuchse  is  a  name  given  to  a  thick  elastic  band 
(not  a  true  ligament)  which  stretches  from 
the  occipital  protuberance  to  the  seventh 
spinous  process.  It  helps  to  sustain  the 
weight  of  the  head  while  bending  forward, 
and  is  particularly  well  developed  in  the 
larger  grazing  animals. 

From  the  seventh  cervical  down  to  the  sacrum 
a  supraspinous  ligament  is  stretched,  attached  to  all 
the  spinous  processes. 

The  movements  of  the  spinal  column  are 
flexion,  extension,  lateral  flexion,  and  rota- 
tion. Motion  is  freest  in  the  cervical  re- 
gion, and  most  restricted  in  the  dorsal. 

Clinical  note. — The  limited  motion  be- 
tween neighboring  bones  becomes  a  wide 
range  in  the  column  as  a  whole  and  may 
be  increased  by  frequent  and  judicious  ex- 
ercises. 


THE  SPINE  AND  THE  SPINAL 
CURVES 


The  length  of  the  spine  is  about  2 7  inches. 
The  solid  portion  is  a  flexible  and  elastic 
column  which  bears  the  weight  of  the  head 
and  its  delicate  organs  without  giving  them 
the  full  force  of  the  jar  caused  by  walking, 
running,  etc.  The  flexibility  of  the  column 
allows  the  whole  body  to  move  with  freedom  and  grace,  while  the 
strength  of  the  spine  makes  it  suitable  for  the  attachment  of  the 
extremities.  The  arches,  connected  by  their  ligaments,  enclose 
the  spinal  or  neural  canal,  which  extends  through  the  sacrum  to 


FIG.  39. — SPINE 
AND  SPINAL  CURVES. 
—{Sappey.} 


44  ANATOMY   AND    PHYSIOLOGY 

the  base  of  the  coccyx.  Since  the  spinal  canal  contains  the  spinal 
cord  there  must  be  places  of  exit  for  the  spinal  nerves;  these  are 
found  in  the  intervertebral  foramina  between  the  roots  of  the 
arches. 

The  spine  has  four  curves:  cervical,  thoracic,  lumbar,  and  sacral. 
These  are  normal  curves. 

The  cervical  and  lumbar  curves  are  concave  posteriorly,  as  is 
seen  to  a  slight  degree  in  the  back  of  the  neck,  and  more  plainly 
in  the  so-called  " small  of  the  back";  while  the  thoracic  and  sacral 
curves  are  concave  anteriorly,  to  accommodate  the  organs  in  the 
thorax  and  pelvis. 

These  curves  are  caused  by  variations  in  the  thickness  of  the  bodies  and 
cartilage  discs.  So-called  "spinal  curvature"  is  an  excessive  or  abnormal 
curve.  If  anterior  it  is  lordosis;  if  lateral,  scoliosis;  if  posterior,  kyphosis. 

A  lateral  curve  usually  exists  in  the  upper  thoracic  region,  but 
this  may  be  called  accidental,  as  it  is  explained  by  the  excessive 
use  of  one  or  the  other  arm. 

THE  TRUNK 

INCLUDES  THE  THORAX,  ABDOMEN  AND  PELVIS 
BONES  OF  THE  THORAX 

Sternum i 

Ribs  (costae) 24 

Thoracic  vertebrae 12 

Sternum  or  breast-bone. — Placed  in  the  front  of  the  thorax. 
It  is  about  6  inches  long,  flat  in  shape  and  structure,  and  its  two 
surfaces  are  called  anterior  and  posterior.  It  has  three  divisions, 
the  manubrium,  the  body,  and  the  xiphoid  appendix  (Fig.  40). 

The  upper  border  of  the  sternum  is  notched — the  sternal  (or 
jugular)  notch;  the  lateral  borders  give  attachment  from  above 
downward  to  the  clavicle  and  the  cartilages  of  the  first  seven  ribs. 
The  xiphoid  appendix  is  the  lowest  portion  of  the  bone  and  gives 
attachment  to  some  of  the  muscles  of  the  abdomen.  It  remains 
cartilaginous  until  middle  life. 

Ribs  (costtz). — Twelve  in  each  side  of  the  thorax,  forming  a 
series  of  movable  elastic  arches.  They  consist  of  a  bony  portion 
(the  costal  bone)  and  a  flexible  portion  (the  costal  cartilage) .  They 
are  flat  in  structure,  curved  in  shape. 


THE  RIBS 


45 


The  posterior  or  vertebral  extremity  is  the  head,  next  to  the 
head  is  the  neck,  and  the  remaining  bony  portion  is  the  shaft. 
The  inner  surface  of  the  shaft  is  marked  by  a  groove  at  its  lower 
border  (the  costal  groove)  in  which  the  intercostal  nerves  and  ves- 
sels run,  being  thus  protected  from  external  injury. 


FIG.  40. — THE  THORAX. 

i,  2,  Manubrium  and  body  of  sternum;  3,  xiphoid  appendix;  4,  circumference  of 
apex  of  thorax;  5,  circumference  of  base;  6,  first  rib;  7,  second  rib;  8,  8,  third,  fourth, 
fifth,  sixth,  and  seventh  ribs;  9,  eighth,  ninth  and  tenth  ribs,  10,  eleventh  and  twelfth 
ribs;  n,  n,  costal  cartilages. — (Sappey.} 

The  first  seven  are  called  "true  ribs,"  being  connected  in  front 
with  the  sternum  by  their  cartilages.  The  remaining  five  are 
"false  ribs";  the  eighth,  ninth  and  tenth  are  connected  in  front,  each 
to  the  one  above;  the  eleventh  and  twelfth  are  not  connected  with 
anything  in  front,  and  are  called  "floating  ribs." 

Thoracic  vertebrae. — Twelve  in  number;  described  with  the 
bones  of  the  spinal  column. 


46 


ANATOMY  AND   PHYSIOLOGY 


The  seventh  rib  of  the  left  side,  inferior 
surface. 

The  costal  groove  is  seen,  to  the  borders 
of  which  the  intercostal  muscles  are  at- 
tached, thus  completing  a  channel  for  in- 
tercostal vessels  and  nerve. 

The  tubercle  is  at  the  beginning  of  the 
shaft;  the  articular  surface  marked  a  is  a 
part  of  the  tubercle. 


FIG.  41.— THE  SEVENTH  RIB. 
a,  articular  surface  for  transverse  process;  b,  neck. — (Morris.) 


THE  THORAX  47 

ARTICULATIONS  OF  THE  THORAX 

Sternum. — The  three  pieces  (manubrium,  body,  and  xiphoid 
appendix)  are  connected  together  by  fibro-cartilages  and  anterior 
and  posterior  ligaments.  After  middle  life  they  become  united  in 
one  bone. 

Ribs  (costce). — The  costal  cartilages  are  connected  in  front  to 
the  sternum,  or  to  each  other,  as  already  mentioned.  The  heads 
articulate  with  the  bodies  of  two  thoracic  vertebrae.  (Exceptions: 
the  first,  eleventh,  and  twelfth  are  each  connected  to  one  body.) 
Where  the  neck  of  the  rib  joins  the  shaft  (marked  by  a  tubercle) 
it  rests  against  the  tip  of  the  transverse  process  of  a  vertebra  behind 


Head  of  rib 


Articular  surface  of 
transverse  process 


Inter-articular  liga- 
ment 


FIG.  42. — HEADS  OF  RIBS  ARTICULATING  WITH  TWO  VERTEBRAE. — (After  Morris.} 

it,  which  thus  forms  a  brace  for  it.  All  of  these  joints  are  enclosed 
by  capsules  and  lined  with  synovial  membrane,  providing  for  the 
movements  of  the  ribs  in  breathing,  talking,  etc.  (Figs.  40,  42.) 

Vertebrae.— Their  joints  have  been  described. 

By  the  articulation  of  the  ribs  with  the  spine  at  the  back  and 
the  sternum  in  front,  the  bony  thorax  is  completed.  It  is  shaped 
like  a  cone,  flattened  before  and  behind,  and  shortest  in  front 
(the  sternum  reaching  only  as  low  as  the  ninth  dorsal  vertebra). 
The  intervals  between  the  ribs  are  called  the  intercostal  spaces. 

The  elasticity  of  the  ribs  and  cartilages  and  their  gliding  joints 
give  a  yielding  character  to  the  thoracic  walls  to  accommodate  the 
movements  of  the  lungs  within. 


48  ANATOMY   AND    PHYSIOLOGY 

BONES  OF  THE  ABDOMEN 

The  five  lumbar  vertebrae/  already  described. 
BONES  OF  THE  PELVIC  GIRDLE 

[  Hip  bones 2 

The  bones  are <j  Sacrum i 

I  Coccyx i 

Hip-bone  (os  coxce).< — Consisting  of  three  parts  which  are 
entirely  separate  in  the  child.  They  are  the  os  ilium,  the  os  ischii, 
and  the  os  pubis;  they  unite  to  form  a  cup-shaped  cavity  called 
the  acetabulum,  seen  on  the  lateral  surface  of  the  bone.  The 
acetabulum  is  the  socket  of  the  hip-joint  (Fig.  43). 


FIG.  43. — HIP-BONE,  EXTERIOR. — (Morris.} 

The  os  ilium  is  the  highest  part  of  the  hip-bone  and  has  a  broad 
expanded  portion  called  the  wing  (or  ala).  The  medial  surface 
of  the  wing  is  the  iliac  fossa,  which  is  filled  with  the  iliac  muscle; 
the  lateral  surface  is  crossed  by  three  curved  lines  (called  the  pos- 
terior gluteal,  the  anterior  gluteal,  and  the  inferior  gluteal  lines). 

The  superior  border  is  called  the  crest.  It  can  be  easily  felt, 
and  the  anterior  extremity  is  known  as  the  anterior  superior  iliac 
spine,  more  often  called  the  spine  of  the  ilium. 

The  os  pubis  is  the  anterior  division  of  the  hip-bone.     It  has 


OS   COX.E  49 

a  body  and  two  branches,  or  rami.  The  body  joins  the  ilium,  the 
superior  ramus  has  a  short  projection  called  the  spine  of  the  pubes, 
and  the  inferior  ramus  extends  downward  and  backward  to  join 
the  ischium,  thus  forming  the  upper  part  of  the  pubic  arch.  The 
two  pubic  bones  join  each  other  in  the  median  line,  forming  the 
pubic  symphysis  (symphysis  pubis). 


Os  ilium 


Os  pubis 

Os  ischii 


Tuberosity 

FIG.  44. — HIP-BONE,  INTERIOR,  BEFORE  UNION  OF  PARTS. — (Morris.} 

The  os  ischii  (or  the  ischium),  the  lowest  part  of  the  hip-bone, 
has  a  sharp  spine  projecting  backward,  a  tuberosity  upon  which 
the  trunk  rests  in  the  sitting  position,  and  a  ramus  which  joins  the 
pubic  ramus  to  complete  the  pubic  arch. 

The  ilium,  ischium,  and  pubes  united  form  the  hip-bone  (os  coxae) . 
Two  large  notches  are  seen  on  the  posterior  border  of  the  completed 
bone,  separated  by  the  spine  of  the  ischium  and  called  the  sciatic 
notches.  The  upper  one  is  the  greater  and  the  lower  one  is  the  lesser 
sciatic  notch.  In  front  of  the  acetabulum  is  the  obturator  foramen, 
the  largest  foramen  in  the  skeleton.  It  is  almost  entirely  closed  by 
the  obturator  membrane,  which  is  composed  of  white  fibrous  tissue. 

THE  ARTICULATIONS  OF  THE  PELVIS 

The  two  hip-bones  unite  with  each  other  in  front  at  the  pubic 
symphysis,  but  the  sacrum  is  between  them  in  the  back,  having 

4 


5O  ANATOMY  AND   PHYSIOLOGY 

the  coccyx  attached  to  its  apex,  and  thus  the  pelvic  girdle  is  formed, 
usually  called  the  pelvis  (or  basin).  These  joints  have  no  cavity, 
and  are  only  slightly  movable,  or  yielding.  There  is  a  distinct 
disc  of  nbro-cartilage  at  the  pubic  symphysis. 


Greater  sacro- 
sciatic  ligament 


Lesser  sacro-sci- 
atic  ligament 


Tendon  of  biceps  muscle 

FIG.  45. — GREATER  AND  LESSER  SACRO-SCIATIC  LIGAMENTS  AND  FORAMINA. — (Morris.) 

Obstetric  note. — The  pubic  symphysis  and  the  sacro-iliac  symphysis 
probably  soften  slightly  during  pregnancy.  The  sacro-coccygeal  joint  has 
limited  motion  until  middle  life  advances,  when  it  may  become  fixed. 

Sacro-sciatic  ligaments  (Fig.  45). — Two  strong  bands  are  stretched 
between  the  sacrum  and  the  ischium.  They  have  no  connection  with  any 
joints  but  are  called  the  greater  and  the  lesser  sacro-sciatic  ligaments.  The 
greater  (ligamentum  sacro-tuberosum)  extends  from  the  borders  of  the  sacrum 
and  coccyx  to  the  tuber osity  of  the  ischium;  the  lesser  (ligamentum  sacro- 
spinosum)  is  placed  immediately  in  front  of  it,  extending  from  the  sacrum 
and  coccyx  to  the  spine  of  the  ischium.  Thus  are  formed  two  foramina  with 
the  lesser  ligament  between  them,  the  one  above  being  called  the  greater 
sciatic  foramen,  and  the  one  below  the  lesser  sciatic  foramen.  (The  sciatic 
nerves  pass  through  the  greater  foramen.) 

Poupart's  ligament,  or  the  inguinal  ligament,  may  be  felt  like 
a  tight  cord  stretched  between  the  spine  of  the  ilium  and  the  spine 
of  the  pubis—  "from  spine  to  spine." 


THE  PELVIS  51 

The  Pelvis  or  Pelvic  Girdle 

False  pelvis. — The  upper  part,  between  the  wings  of  the  ilia. 
It  is  broad  and  shallow. 

True  pelvis.^The  lower  part,  bounded  by  the  pubes  in  front, 
the  ischia  at  the  sides,  and  the  sacrum  and  coccyx  at  the  back.  It 
is  deeper  and  narrower. 

The  female  pelvis  has  lighter  bones,  a  wider  pubic  arch,  and 


FIG.  46—  THE  PELVIS.— (Morris.} 


greater  capacity  than  the  male  pelvis;  the  sacrum  is  less  curved  and 
the  sacral  promontory  less  projecting. 

The  limiting  line  or  boundary  between  the  false  and  the  true  pelvis 
is  a  curved  line  called  the  brim,  and  the  space  included  is  the  inlet; 
the  lower  opening  is  the  outlet.  The  inlet  and  the  outlet  are  also 
known  as  the  superior  and  inferior  straits.  The  measurements  or 
diameters  of  these  straits  in  the  female  pelvis  are  as  follows : 

INLET  (Edgar's  Obstetrics) 

Antero-posterior 1 1  cm. 

(Symphysis  to  promontory.) 
Oblique \2\  cm. 

(Ilio-pectineal  joint  to  sacro-iliac  joint.) 
Transverse 13!  cm. 

(Widest  part  of  brim.) 


5- 


Am  ore-posterior 

(Sympbysis  to  tip  of  coccyx.) 
Transverse 

(Between  tuberosities.) 


ii  cm. 


Fte.  47. — THE  PELVIS.    INLET, 


>R  STRAIT. — ($ 


i.  Iliac  fossa;  2,  crest  of  ilium;  3,  anterior-superior  spine  of  ilium;  4,  anterior- 
inferior  spine  of  ilium;  5,  ilio-pectineal  joint;  6,  7,  body  and  symphysis  of  pubes; 
S,  acetabulum;  o,  tuber  of  isrhnim;  10,  n,  pubic  arch:  i:.  spines  of  isclv. 
coccyx;  14,  saooOiac  joint;  15,  is  placed  just  above  the  promo: . 


•--  :• •--  :    '   •  '  .       -I"..  .i:s 

early  in  the  second  month. 


The  nucleus  for  the  pubis  appears 
about  the  end  of  the  fourth  month 
— -The  nucleus  for  the  ischium  appears 
in  the  thud  month 


FIG.  48. — THE  PELVIS  of  A  FETUS  AT  BIRTH.  TO  SHOW  THE  THREE  PORTI 
THE  COKAL  BOXES.— (Morris.) 


THE  DORSAL  AXD  VENTRAL  CAVITIES  OF  THE  BODY 

By  articulation  of  the  bones  of  the  head  and  trunk  a  framework 
is  formed  for  two  cavities,  within  which  are  situated  the  internal 
organs  or  viscera.  (These  delicate  and  important  parts  must  be 
provided  with  surrounding  structures  which  insure  both  their 
safety  and  efficiency.) 


THE  VENTRAL  CAVITY  53 

The  cavities  are  called  dorsal  and  ventral,  or  neural  and 
visceral.  Briefly  speaking,  they  may  be  described  as  situated 
posteriorly  and  anteriorly  to  the  solid  part  of  the  spinal  column 
or  bodies  of  the  vertebrae. 

The  spinal  canal  is  a  part  of  the  dorsal  or  neural  cavity  which 
extends  into  the  interior  of  the  skull,  the  bones  of  the  cranium  being 
modified  vertebrae,  and  the  cavity  within  them  representing  the 
uppermost  or  cranial  part  of  the  neural  canal. 

The  dorsal  or  neural  cavity  contains  the  brain  and  spinal  cord, 
well  protected  within  firm,  unyielding  walls. 

The  mouth,  neck,  thorax,  abdomen  and  pelvis  inclose  the  ventral 
or  visceral  cavity,  which  is  in  front  of  the  spinal  column.  The 
bony  walls  are  very  incomplete,  especially  in  the  abdomen.  They 
are  finished  out  by  muscles;  this  arrangement  allows  the  walls  to 
be  flexible  and  yielding  in  character,  thus  securing  to  the  organs 
contained  that  freedom  of  movement  which  is  necessary  to  their 
perfect  action.  The  diaphragm  (page  97)  divides  the  ventral 
cavity  into  two  portions,  upper  and  lower;  the  pelvic  floor  (page 
no)  completes  the  boundary  below. 

The  ventral  cavity  contains  the  organs  of  respiration,  circula- 
tion, digestion  and  reproduction;  also  the  kidneys  and  bladder, 
which  are  organs  of  elimination. 

Having  studied  the  bones  of  the  dorsal  and  ventral  cavities  or 
those  of  the  head  and  trunk,  we  will  proceed lin  Chapter  IV  to 
those  of  the  extremities. 


CHAPTER  IV 

BONES  AND  ARTICULATIONS  OF  THE  EXTREMITIES 
BONES  OF  THE  UPPER  EXTREMITY 

The  upper  extremity,  as  the  artist  sees  it,  begins  with  the  arm. 
The  anatomist  includes  the  shoulder  as  a  part  of  the  extremity. 
The  bones  are  therefore  as  follows : 


In  the  shoulder 


j  clavicula 


In  the  forearm . 


In  the  arm  ...........      humerus 

radius 

ulna 

scaphoid 

semilunar 

cuneiform 


pisiform 


ist  row.. . 


In  the  wrist  or  carpus 


2d  row. . 


8 


In  the  hand. 


trapezium 

trapezoid 

os  magnum 

unciform 

J  palm  or  metacarpus  (metacarpal  bones)  5 
I  fingers  or  digits  (phalanges) 14 

32 


The  names  of  -'carpal  bones  are  given  as  follows  in  Spalteholz's  Hand 
Atlas: 

ist  row — os  naviculare  manus.      2nd  row — os  multangulum  majus. 
os  lunatum.  os  multangulum  minus. 

os  triquetrum.  os  capitatum. 

os  pisiforme.  os  hamatum. 

Note. — The  end  of  a  bone  which  is  nearest  to  the  trunk  is  called  the 
proximal  extremity;  the  other  end  is  the  distal  extremity.  The  same  terms 
are  applied  to  surfaces. 

THE  SHOULDER  OR  SHOULDER-GIRDLE 

Scapula,  or  shoulder-blade  (Fig.  49). — Placed  at  the  upper 
part  of  the  chest,  behind  the  ribs  (from  the  second  to  the  eighth). 
It  is  flat  and  irregular  in  structure,  and  triangular  in  shape. 

54 


SCAPULA,   CLAVICULA 


55 


The  margins  are  called  the  superior,  the  vertebral,  and  the  axillary;  the 
angles,  lateral,  medial,  and  inferior.  The  inferior  angle  and  vertebral  border 
or  margin  usually  project  a  little  backward,  sometimes  very  notably,  making 
the  so-called  "winged  scapula." 

The  anterior  surface  (costal  surface)  is  called  the  subscapular 
fossa,  and  is  filled  with  the  subscapular  muscle.  The  posterior  or 

dorsal  surface  is  crossed  by  a  rough 
ridge  called  the  spine  of  the  scapula 
which  terminates  in  an  important 
process,  the  acromion,  overhanging 
the  shoulder-joint. 

Below  and  in  front  of  the  acromion  is 
the  coracoid  process. 


FIG.  49. — SCAPULA,  POSTERO-  FIG.  50. — CLAVICLE,  INFERIOR  ASPECT. 

EXTERNAL  ASPECT.  ^  Longitudinal  depression  for  insertion 

i,    Supraspinous    fossa;    2,    infra-  of  subclavius  muscle;  2,  rough  impression 

spinous  fossa;  3,  superior  or  coracoid  for  attachment  of  costoclavicular  ligament; 

border;  4,   coracoid  or  suprascapular  3,   3,   for  attachment  of  coraco-clavicular 

notch;   5,   axillary  or  lateral   border;  ligaments;  4,  4,  posterior  border;  5,  5,  an- 

6,  anterior  angle  and  glenoid  cavity;  terior  border;  6,  facet  for  articulation  with 

7,  inferior  angle;  8,  rough  impression  sternum;    7,    facet    for    articulation    with 
for  long  head  of  triceps;  9,  medial  or  acromion. — (Sappey.} 

spinal  or  vertebral  border;  10,  spine; 
n,  smooth  surface  over  which  tra- 
pezius  muscle  glides;  12,  acromion;  13, 
base  of  spine;  14,  coracoid  process. — 
(Sappey.} 

The  lateral  angle  presents  a  shallow  depression  called  the 
glenoid  cavity.  This  cavity  forms  the  socket  of  the  shoulder-joint. 

Clavicula  (or  collar-bone,  Fig.  50).— Long  in  shape,  but  having 
no  medullary  canal.  It  is  curved  like  an  italic  letter  /  and  placed 
horizontally  across  the  front  of  the  upper  ribs.  The  medial  ex- 
tremity articulates  with  the  sternum  and  is  therefore  called  the 
sternal  extremity.  The  lateral  extremity  articulates  with  the 
acromion  process  of  the  scapula,  and  is  called  the  acromial 
extremity. 

Clinical  note. — The  weight  and  curves  are  increased  by  exercise, 
and  both  bones  are  usually  more  developed  in  men  than  in  women. 


ANATOMY   AND    PHYSIOLOGY 


The  clavicula  is  easily  broken,  especially  in  children,  being  fre- 
quently the  seat  of  " green-stick "  fracture.     (See  p.  77.) 

The  clavicula  and  scapula  together  form  the 
shoulder-girdle,  which  is  open  at  the  back, 
but  closed  in  front  by  the  sternum  placed  be- 
tween the  two  claviculag. 


THE  ARM  OR  BRACHIUM 

Humerus.-  —  Long  in  structure  and  shape, 
having  a  shaft  with  a  medullary  canal  and  two  ex- 
w  *  *  f  tr  entities. 

The  upper  extremity  (proximal  extremity) 
includes  the  head,  neck  and  tubercles. 

The  head  articulates  with  the  glenoid  cavity 
of  the  scapula  to  form  the  shoulder-joint;  the 
short,  thick,  anatomic  neck  joins  the  head  to  the 
shaft,  and  just  below  the  neck  are  the  greater  and 
lesser  tubercles  for  the  attachment  of  muscles  to 
abduct  and  rotate  the  arm.  The  lower  extremity 

FIG.    51.—  LEFT  curves  slightly  forward  and  presents  two  pro- 
HUMERUS,       ANTE- 
RIOR ASPECT.  jections  at  the  sides  called  the  medial  and  lateral 

i,  Shaft  or  body;  epicondyles;  the  medial  is  the  longer  and  conse- 

2,  head;  3,  anatomic 

neck;  4,  greater  tu-  quently  it  is  more  frequently  broken  off.  Be- 
bercle-  6*  ^7***  ^  tween  tne  epicondyles  are  the  articular  surfaces 
markings  for  mus-  for  the  elbow-joint,  the  trochlea  for  the  ulna  and 

cles;   10,  orifice  for  . 

nutrient  artery;  n,  the  capttulum  for  the  radius. 

cWea^111!/  lateral  The   Shaft   haS    thre6  borders  and  three  sur~ 

and  medial  epicon-  faces  like  that  of  all  long  bones  (on  the  fibula 
andmedial  'borfSS  a  fourth  border  and  surface  are  described). 


The  anterior  and  medial  borders  run  from  the  greater 
and  lesser  tubercles.  In  the  upper  part  they  are  called 
the  crests  of  the  tubercles  and  the  groove  for  the  long  tendon  of  the  biceps 
muscle  is  between  them  (formerly  called  bicipital  groove  as  the  borders  were 
called  bicipital  ridges). 

The  broad,  shallow  groove  containing  the  radial  nerve  winds 
across  the  posterior  surface. 

Note.  —  The  slender  portion  of  the  shaft  just  below  the  tubercles 
is  called  the  surgical  neck,  because  it  is  so  often  fractured. 


ULNA,  RADIUS 


57 


i" 


FOREARM,  OR  ANTEBRACHIUM 

* 
Ulna. — A  long  bone  in  structure  and  form,  situated  in  the 

medial  side  of  the  forearm  (the  ulnar  side).  The  upper  extremity 
presents  two  strongly  marked  processes — the  olecranon,  pro- 
jecting upward  from  the  back  and  curving 
forward,  and  the  coronoid,  projecting  forward 
from  the  front  and  curving  upward.  Thus 
these  processes  curve  toward  each  other,  and 
the  cavity  between  them  is  the  semilunar 
notch.  It  receives  the  trochlea  of  the  humerus 
to  form  the  elbow-joint.  On  the  lateral  side 
of  the  coronoid  process  is  the  radial  notch, 
where  the  head  of  the  radius  lies. 

The  lower  extremity  is  the  head  of  the 
ulna,  which  lies  in  the  ulnar  notch  of  the  ra- 
dius. There  is  a  well-marked  projection  on 
this  head  called  the  styloid  process. 

The  posterior  border  of  the  shaft  is  subcutaneous 
and  may  be  traced  down  from  the  point  of  the  elbow. 
The  space  between  the  radius  and  the  ulna  is  called 
the  interosseous  space,  and  is  occupied  by  an  interos- 
seous  membrane. 


Radius.- — A  long  bone  in  structure  and  in 
form,  situated  on  the  lateral  side  of  the  forearm 
(the  radial  side). 

The  upper  (or  proximal)  extremity  is  the 
head,  which  is  depressed  at  the  top  to  fit  the 
capitulum  of  the  humerus.  Below  the  head  is 
the  neck,  and  below  that,  in  front,  is  the 
tuberosity  of  the  radius  for  the  attachment  of 
the  biceps  muscle  of  the  arm.  The  lower  (or 
distal)  extremity  of  the  radius  is  broad  and 
thick,  and  is  the  largest  bone  in  the  formation 
of  the  wrist-joint. 


On  its  lateral  aspect  is  the  styloid  process.  Run- 
ning across  the  upper  half  of  its  anterior  surface  is 
the  oblique  line,  which  is  a  part  of  the  anterior  border. 

Special  notes. — The  head  of  the  humerus  is  proximal  and  articulates  with 


FIG.  52.— LEFT 
ULNA  AND  RADIUS, 
ANTERIOR  SUR- 
FACES.— (Sappey.) 

i,  Shaft  or  body 
of  ulna;  2,  semilunar 
notch;  3,  radial 
notch  occupied  by 
radial  head;  4,  olec- 
ranon;  5,*  coronoid 
process;  6,  orifice 
for  nutrient  artery; 

7,  interosseous  bor- 
ders    with    interos- 
seous space  between; 

8,  head  of  ulna;  9, 
styloid    process    of 
ulna;    10,    shaft  or 
body  of  radius;  n, 
12,  head   and  neck 
of  radius;    13,     tu- 
berosity   of    radius; 
14,  marking  for  mus- 
cle; 15, 16,  lower  ex- 
tremity and  styloid 
process. 


58  ANATOMY   AND    PHYSIOLOGY 

the  glenoid  cavity  of  the  scapula.     The  head  of  the  radius  is  proximal  and 
articulates  with  the  humerus.     The  head  of  the  ulna  is  distal. 

The  upper  end  of  the  ulna  is  its  largest  part,  and  an  important  bone  in  the 
elbow-joint.  The  lower  end  of  the  radius  is  the  largest  part,  and  important  in 
the  wrist-joint.  Observe  that  in  the  long  bones  of  the  upper  extremity  the 
nutrient  foramina  are  in  the  shafts  and  are  directed  toward  the  elbow-joint. 
They  transmit  nutrient  arteries  to  nourish  the  bones. 

CARPUS 

The  carpal  bones  (ossa  carpi)  are  eight  in  numfygr.  and  are 
typical  "slwrt  tones.  They  are  arranged  in  two  slightly  curved 

rows — the  first  and  second — with  the  con- 
vexity of  the  curves  turned  upward  to- 
ward the  radius,  the  first  row  articulating 
with  it. 

FIRST  Row 

Navicular  (os  namculare). — On  the 
radial  side  of  the  wrist,  named  from  its 
shape  which  resembles  a  boat,  and  marked 
by  a  tubercle. 

FIG  —  BONES  OF  Semilunar  (os  lunatu m) . — Well  named 
CARPUS,  DORSAL  SURFACE,  from  its  half-moon  shape. 

Cuneiform      (os      triquetrum). — Very 
slightly  resembling  a  wedge. 

Pisiform  (os  pisiforme). — Resembling  the  half  of  a  split  pea, 
and  placed  in  front  of  the  cuneiform. 

SECOND  Row 

Trapezium  (os  multangulum  majus). — On  the  radial  side, 
marked  by  a  ridge. 

Trapezoid  (os  multangulum  minus). — The  smallest  of  the 
carpal  bones. 

Os  magnum  (os  capitatum).- — The  largest,  having  head,  neck, 
and  body. 

Unciform  (os  hamatum). — Named  for  its  unciform  or  hook- 
shaped  process. 

When  the  carpus  is  seen  from  the  front,  four  prominent  points 
are  to  be  noted,  namely — the  tubercle  of  the  navicular  and  ridge 


BONES  OF  THE  HAND 


59 


of  the  trapezium,  on  the  radial  side;  the  pisiform  bone  and  hook 
of  the  unciform  on  the  ulnar  side.  These  mark  the  boundaries  of 
a  deep  groove  where  the  long  tendons  of  the  ringers  glide. 

THE  METACARPUS  OR  PALM 

The  five  metacarpal  bones  (ossa  metacarpalia)  are  long  in 
shape  but  have  no  medullary  canal.  Each  has  a  base,  a  shaft, 
and  a  head,  the  head  being  distal.  The  bases  are  articulated  with 
the  second  row  of  the  carpus,  the  heads 
with  the  first  row  of  the  phalanges.  The 
first  corresponds  to  the  thumb,  the  second 
to  the  index  finger,  the  third  to  the  middle 
finger,  the  fourth  to  the  ring  finger,  and 
the  fifth  to  the  little  finger. 

The  spaces  between  them  are  inter- 
osseous  spaces  and  are  occupied  by  inter- 
osseous  muscles. 

Note. — The  third  metacarpal  bone  (of 
the  middle  finger)  is  the  longest,  and  its 
head  is  the  most  prominent  when  the  hand 
is  clenched,  as  in  making  a  "fist." 


FIG.  54. — RIGHT  HAND,  PAL- 
MAR OR  VOLAR  SURFACE. 


PHALANGES 


These  are  the  bones  of  the  fingers  and  for 
thumb  (digits).  A  finger  has  three,  first,  Carpus;  11-11,  phalanges;  12, 
second  and  third;  the  thumb  has  two,  first  phalanges;  14, 15,  ist  and  2d 
and  second.  They  are  long  in  shape,  but  \sappey  ^  of  thumb-- 
without  a  medullary  canal.  Each  has  a 

base,  a  shaft,  and  a  head,  the  head  being  distal.  The  first  row 
of  phalanges  includes  those  which  are  next  to  the  metacarpal 
bones.  The  terminal  phalanges  (those  of  the  third  row)  have 
each  a  horse-shoe-shaped  border  on  the  anterior  surface  for  the 
support  of  the  sensitive  finger  tip;  because  these  bear  the  nails 
they  are  called  the  ungual  phalanges.1 

1  This  description  of  the  metacarpal  bones  and  phalanges  follows  that  of  standard 
text-books.  It  would  seem,  however,  more  in  accordance  with  the  facts  to  con- 
sider the  palm  as  composed  of  four  metacarpal  bones — one  for  each  finger — and  to 
give  to  the  thumb  three  phalanges,  since  the  bone  commonly  called  the  first  metacarpal 
(or  the  metacarpal  of  the  thumb)  resembles  those  of  the  first  row  of  the  phalanges  in 
both  form  and  development. 


6o 


ANATOMY  AND   PHYSIOLOGY 


Resume. — With  the  limb  in  the  anatomic  position,  observe  the  groove 
for  the  biceps  muscles  on  the  front  of  the  humerus,  beginning  between  the 
greater  and  lesser  tubercles.  In  the  forearm,  note  that  the  ulna  is  the  bone  of 
the  elbow-joint,  while  the  radius  makes  the  wrist-joint;  that  their  shafts  are 
parallel  and  the  palm  is  turned  forward,  and  the  carpus  curved  to  help  in 
forming  the  hollow  of  the  hand  (or  the  "cup  of  Diogenes"),  and  that  the 
thumb  is  on  the  radial  side,  and  free. 

ARTICULATIONS  OF  THE  UPPER  EXTREMITY 

Sterno-clavicular,  a  gliding  joint  (arthrodia) . — This  is  the  one 
joint  by  which  the  upper  extremity  articulates  with  the  trunk. 

Articular  surfaces;  on  the  upper  angle  of  the  manubrium  and 
the  sternal  end  of  the  damcula.  Anterior  and  posterior  ligaments 


Inter-articu- 
lar ligament 


Sterno-cos- 
tal  joint 


FIG.  55. — STERNO-CLAVICULAR  JOINT. — (Morris.) 

The  inter-articular  cartilage  is  shown  in  the  joint  of  the  right  side;  capsules  shown 

on  the  left  side. 

connect  the  bones,  forming  a  capsule.  (The  joint  is  divided  by  a 
disc  of  fibro-cartilage  into  two  cavities  and  there  are  two  synovial 
membranes.) 

Motions. — Gliding,  by  which  the  shoulder  moves  upward, 
downward,  backward  and  forward. 

Ligaments  not  connected  with  the  joint  but  useful  in  preventing  dislocation: 
— Thecosto-davicular,  holding  the  clavicle  to  the  first  rib,  and  the  conoid  and 
trapezoid  connecting  it  with  the  coracoid  process  of  the  scapula.  (See  Fig.  56.) 

Acromio-clavicular. — A  small  gliding  joint  between  the 
acromion  process  of  the  scapula  and  the  acromial  end  of  the  damcula. 
It  is  enclosed  by  a  capsule. 

Shoulder-joint. — A  ball-and-socket  joint  (enarthrosis) .     Artie- 


SHOULDER-   AND    ELBOW-JOINTS 


6l 


ular  surfaces:  the  head  of  the  humerus  and  the  glenoid  fossa  of  the 
scapula.  The  fossa  is  deepened  by  a  rim  of  fibro-cartilage  called 
the  glenoid  margin.  The  capsule  is  attached  to  the  scapula  around 
the  margin  of  the  glenoid  fossa,  and  to  the  humerus  around  the 
anatomic  neck.  It  is  so  loose  that  the  head  of  the  humerus  will 

Conoid  ligament 


Superior  transverse 

scapular  ligament 


Trapezoid  ligament 


Coraco-acromial  ligament 


Short  head  of  biceps 
Subscapular  tendon 

Capsule  of  shoulder 


Long  tendon  of  biceps 


FIG.  56. — ANTERIOR  VIEW  OF  SHOULDER,  SHOWING  ALSO  CORACO-CLAVICULAR  AND 
CORACO-ACROMIAL  LIGAMENTS. — (Morris.') 

fall  an  inch  away  from  the  glenoid  fossa  by  its  own  weight,  if  the 
surrounding  muscles  be  removed;  it  contains  a  synovial  mem- 
brane which  covers  the  glenoid  margin  and  folds  like  a  sheath 
around  the  long  tendon  of  the  biceps  muscle  (Fig.  56). 

Motions. — In  every  possible  direction,  as  flexion,  extension,  ab- 
duction, adduction,  rotation,  and  circumduction,  with  greater  free- 
dom than  any  other  joint  of  the  body,  because  the  socket  is  so 
shallow  and  the  capsule  is  so  loose. 

Elbow- joint. — A  hinge-joint  (ginglymus)  (Fig.  57). 

Articular  surfaces:  the  trochlea  of  the  humerus  in  the  semilunar 
notch  of  the  ulna;  the  capitulum  of  the  humerus  in  the  depressed 
head  of  the  radius. 


62  ANATOMY   AND   PHYSIOLOGY 

The  ligaments — anterior,  posterior,  medial,  and  lateral — to- 
gether compose  a  large  capsule.  (They  are  attached  to  the 
humerus  above  the  olecranon  fossa  at  the  back,  and  above  the  coro- 
noid  and  radial  fossae  in  front.)  The  synomal  membrane  is 
extensive. 


Annular  ligament 
Tendon  of  biceps 

Oblique  ligament 

Upper  edge  of  inter- 
osseous  membrane 


Flo.  57. — MEDIAL  VIEW  OF  THE  ELBOW-  JOINT  .—(Morris.} 

Motions. — The  elbow-joint  proper  is  capable  of  flexion  and 
extension  only,  like  all  hinge-joints. 

The  radius  and  ulna  are  connected  together  at  their  extremities,  making 
rolling  joints  (see  p.  18);  their  shafts  give  attachment  to  an  interosseous 
membrane  of  white  fibrous  tissue  which  almost  fills  the  space  between  the 
bones. 

Wrist- joint. — Between  the  forearm  and  the  carpus,  having  a 
variety  of  gliding  motions,  but  used  principally  as  a  hinge-joint. 
Articular  surfaces:  Above — the  lower  end  of  the  radius  and  the 
triangular  cartilage  (or  articular  disc) ;  below — the  first  row  of  carpal 
bones  (not  including  the  pisiform) .  The  ligaments — anterior  pos- 
terior, medial,  and  lateral — enclose  the  joint  like  a  capsule. 

Motions. — Flexion,  extension,  and  slight  lateral  bending  (or 
from  side  to  side)  making  abduction  and  adduction.  (If  the  hand 
is  bent  far  backward  or  over-extended,  this  is  dorsal  flexion.) 


CARPAL,   METACARPAL  AND  PHALANGEAL  JOINTS 


Surgical  note. — The  anterior  ligament  of  the  wrist-joint  is 
remarkably  strong  and  seldom  torn;  the  lower  end  of  the  radius 
breaks  instead,  under  sudden  great  force,  as  in  Colics'  fracture. 

Carpal. — Eight  bones  arranged  in  two  rows,  bound  firmly  to- 
gether by  short  ligaments.  Motions — Gliding  only. 

Metacarpal. — Five  bones,  articulated  by  their  bases  to  the 
carpus,  and  by  their  heads  to  the  digits.  Head  of  first,  belong- 
ing to  thumb,  is  free;  heads  of  others  connected  together  by  a 
transverse  band.  Motions — Slight  gliding,  except  in  case  of  the 


Ulnar  radio-ulnar 
ligament    . 

Ulnar  collateral  lig- 
ament of  wrist 
Flexor  carpi  ulnaris 


Radial  collateral 

ligament  of  wrist 
Volar  radio  carpal 

ligament 

Tendon  of  fl  e  x  o  r 
carpi  radialis 

Capsular  ligament 
of  first  carpo-met- 
acarpal  joint 


FIG.  58.— ANTERIOR  VIEW  OF  WRIST. — (Morris.} 

thumb,  which  may  be  flexed  or  bent  upon  the  palm;  extended 
or  straightened;  abducted  from  hand;  adducted  toward  hand. 

Surgical  note. — In  the  normal  hand,  a  dislocation  of  the  thumb 
is  most  difficult  of  reduction,  because  the  metacarpal  head  and 
the  base  of  the  first  phalanx  are  interlocked  in  such  a  manner 
as  to  form  what  is  called  a  joint  by  reciprocal  reception,  or  "  saddle 
joint." 

Phalangeal.- — Three  bones  in  each  finger,  two  in  the  thumb. 
Anterior,  posterior,  and  lateral  ligaments.  Motions — Flexion  and 
extension. 


64 


ANATOMY   AND   PHYSIOLOGY 


Note. — In  the  completed  hand,  the  fingers  and  the  thumb  can 
be  moved  from  side  to  side,  independently;  that  is,  they  can  be 
spread  apart  (abduction)  and  drawn  together' (adduction)  (p.  18). 

SUPINATION  AND  PRONATION 

These  are  terms  applied  to  certain  movements  of  the  ex- 
tremities. They  are  best  seen  in  the  forearm  where  they  change 
the  position  of  the  hand. 

The  head  of  the  radius  rests  in  the  radial  notch  of  the  ulna, 
held  there  by  a  circular  band  called  the  ring  ligament  (orbicular), 
and  it  can  be  rolled  forward  or  backward,  within  the  ring  (a  form 
of  pivot  joint) .  Of  course,  the  shaft  moves  at  the  same  time,  the 
lower  end  turning  forward  or  backward  around  the  head  of  the 
ulna,  and  the  wrist  and  hand  must  accompany  it.  When  the 
radius  and  the  ulna  are  placed  in  the  anatomic  position,  their 
shafts  are  parallel  and  the  hand  lies  upon  its  back;  this  is  supina- 
tipn.  If  the  radius  rolls  forward,  the  shafts  become  crossed,  and 
the  hand  lies  upon  its  face;  this  is  pronation. 

Surgical  notes. — Supination  and  pronation  are  very  important 
movements.  If  they  are  prevented  the  hand  loses  much  of  its 
usefulness,  therefore  fractures  of  the  shafts  should  not  be  set  in 
the  position  of  pronation,  lest  adhesions  form  between  the  crossed 
shafts,  preventing  supination. 


BONES  OF  THE  LOWER  EXTREMITY 

In  the  Thigh Femur i 

In  the  Leg |  Tibia 

1  Fibula 

Talus 

Calcaneus 

]  Cuboid 

In  the  Tarsus j  Navicular  bone. . 

ist  cuneiform... . 

2d  cuneiform. . . 

3d  cuneiform. . . 

Metatarsus .......      Metatarsal  bones 5 

Toes  or  Digits Phalanges 14 

Patella .  ,  A  sesamoid  bone.  i 


ist  row. . . 


2d  row. . 


THE    FEMUR 


As  given  by  Spalteholtz  the  names  of  tarsal  bones  are: — 


Talus 
Calcaneus 
(os  calcis) 


ist  row 


Os  cuboideum 
Os  naviculare  pedis 
Os  cuneiforme     I 
Os  cuneiforme    II 
Os  cuneiforme  III 


2d  row 


THE  THIGH 

Femur. — The  largest  bone  in  the  body. 

Its  upper  extremity  presents  a  nearly  spherical  head  joined 
by  a  neck  to  the  shaft,  and  resting  in  the  acetabulum.     At  the 


FIG.  59. — THE    FEMUR,    LEFT    POS- 
TERIOR ASPECT. 

i,  i,  Linea  aspera;  2,  2,  3,  divisions 
of  linea  aspera;  4,  4,  divisions  of  linea 
aspera;  5,  6,  head,  and  mark  for  liga- 
mentum  teres;  7,  neck;  8,  9,  trochanter 
major;  10,  trochanter  minor;  n,  12,  lat- 
eral and  medial  condyles;  13,  intercon- 
dyloid  notch;  14,  15,  lateral  andjnedial 
epicondyles. — (Sappey.) 

5 


FIG 


60. — LEFT  TIBIA  AND  FIBULA, 
ANTERIOR  ASPECT. 


i,  Shaft  or  body  of  tibia;  2,  3,  me- 
dial and  lateral  condyles;  4,  spine  or 
intercondyloid  eminence;  5,  tubercle  of 
tibia;  6,  crest  or  shin;  7,  8,  lower  ex- 
tremity, and  medial  malleolus;  9,  shaft 
or  body  of  fibula;  10,  upper  extremity 
or  head  of  fibula;  n,  lower  extremity 
and  lateral  malleolus. — (Sappey.) 


66  ANATOMY   AND   PHYSIOLOGY 

junction  of  the  neck  and  shaft  are  the  two  trochanters — the 
trochanter  major  on  the  lateral  side,  and  the  Irochanter  minor  on 
the  medial  and  posterior  side.  The  lower  extremity  presents  two 
condyles  projecting  downward,  the  medial  and  the  lateral.  The 
medial  is  slightly  longer,  the  lateral  slightly  broader  of  the  two; 
the  deep  notch  between  them  is  called  the  intercondyloid  notch  or 
fossa.  There  is  a  projection  from  the  side  of  each  condyle  called 
the  medial  and  the  lateral  epicondyle. 

The  shaft  has  a  prominent  posterior  border  called  the  linea 
aspera.  This  divides  lower  down  into  two  lines  running  to  the 
condyles  and  enclosing  a  smooth  triangular  space  called  the  pop- 
liteal space,  or  plane  of  the  femur.  The  other  borders  are  not  plainly 
seen. 

THE  LEG  (FiG.  60) 

Tibia. — A  long  bone  in  the  medial  side  of  the  leg.  Its  jipper 
extremity  is  the  head,  which  presents  two  condyles,  medial  and 
•  la lu  crtT^having  shallow  depressions  on  the  top  to  bear  the 
condyles  of  the  femur.  Between  these  depressions  is  the  inter- 
condyloid eminence,  or  spine  of  the  tibia.  The  tuberosity  of  the 
tibia  is  a  large  elevation  in  front,  just  below  the  head.  The  lower 
extremity  has  a  projection  downward  from  its  medial  surface  called 
the  medial  malleolus,  which  helps  to  form  the  ankle-joint. 

The  shaft  has  a  prominent  anterior  border  called  the  crest 
or  shin,  which  is  plainly  felt  under  the  skin.  This  border  and  the 
medial  surface  are  both  called  subcutaneous  because  no  muscles 
cover  them. 

Fibula. — A  long  bone,  in  the  lateral  side  of  the  leg,  slender  and 
easily  broken.  Its  upper  extremity  is  the  head,  which  has  a  short 
styloid  process  pointing  upward.  The  lower  extremity  is  the  lateral 
malleolus,  which  helps  to  form  the  ankle-joint. 

Note. — The  space  between  the  tibia  and  fibula  is  called  the  interosseous 
space,  and  is  occupied  by  interosseous  membrane. 

The  lower  extremities  of  these  two  bones  form  the  prominences 
at  the  side  of  the  ankle  known  as  the  ankle-bones;  they  are  the 
medial  and  the  lateral  malleoli,  which,  being  subcutaneous,  are 
especially  exposed  to  blows. 

Special  notes.— Observe  that  the  heads  of  al]  three  bones  are  proximal; 
that  the  fibula  does  not  form  any  part  of  the  knee-joint;  that  the  nutrient 
foramina  all  run  from  the  knee. 


TALUS    CALCANEUS 


67 


THE  TARSUS  (Fio.  61) 

There  are  seven  tarsal  bones  arranged  in  two  irregular  rows 
to  form  the  arches  of  the  foot,  or  instep. 

FIRST  Row 

Talus  (astragalus). — On  the  tibial  side.  Has  a  head,  a  neck, 
and  a  body;  the  body  is  received  between  the  two  malleoli  to  form 
the  ankle-joint,  and  the  head  is  turned  forward  toward  the  toes. 
It  rests  upon  the  calcaneus. 


Calcaneus 


Talus 


Scaphoid,  or  navicular 


First  cuneiform 


Tarsus 


Metatarsus 


Phalanges 


FIG.  6 1. — BONES  OF  LEFT  FOOT. — (Morris.} 

Calcaneus  (os  calcis)  or  bone  of  the  heel.* — The  largest  tarsal 
bone,  it  is  under  the  talus  (astragalus),  and  bears  the  weight  of 
the  entire  body  in  the  erect  position.  The  tuber osity  of  the  cal- 
caneus projects  backward  beyond  the  ankle,  and  gives  attachment 


68 


ANATOMY   AND    PHYSIOLOGY 


to  the  largest  tendon  in  the  body,  the  tendon  of  Achilles  (tendo 
A  chillis). 

SECOND  Row 

Navicular  (os  namculare) . — On  the  tibial  side,  in  front  of  the 
talus,  articulating  with  its  head. 

Cuneiform  bones  (or  wedge-shaped  bones).- — In  front  of  the 
navicular.  They  are  three  in  number,  first,  second,  and  third. 

Cuboid  (os  cuboideum). — It  lies  in  front  of  the  calcaneus. 

THE  METATARSUS 

The  five  metatarsal  bones  in  the  foot  resemble  the  metacarpal 
bones  of  the  hand  in  their  general  characteristics,  with  some  special 
developments;  the  inter  osseous  spaces  between  them  are  occupied 
by  interosseous  muscles. 

PHALANGES 

Fourteen  in  number,  as  in  the  hand,  and  arranged  in  a  similar 
manner — two  for  the  great  toe,  and  three  for  each  of  the  other 
toes. 


A.  B. 

FIG.  62.  LEFT  PATELLA.  FIG.  63. 

A,  ANTERIOR  SURFACE;  B,  POSTERIOR  SURFACE. — (Morris.) 

Note.- — The  great  toe  is  in  the  medial  border  of  the  foot. 

PATELLA 

The  patella  is  the  largest  sesamoid  bone.  It  is  triangular  in 
shape,  placed  in  front  of  the  knee-joint,  and  held  to  the  tuber- 
osity  of  the  tibia  by  a  strong  band  about  three  inches  long — the 


HIP-JOINT 


69 


Tendon  of  biceps 
muscle 


Capsule 


FIG.  64. — HIP-JOINT. — (Morris.) 


Capsule 
Glenoid  rim 


Ca  psule 


FIG.  65. — LIGAMENTUM  TERES. — (Morris.") 


7O  ANATOMY   AND    PHYSIOLOGY 

so-called  ligament  of  the  patella.  Its  location  while  the  body  is 
erect  is  in  front  of  the  condyles  of  the  femur,  but  in  the  sitting 
position  it  is  in  front  of  the  lower  ends  of  the  condyles,  and  in 
kneeling  it  is  beneath  them. 

ARTICULATIONS  OF  THE  LOWER  EXTREMITY 

Hip-joint  (ball-and-socket  joint)  (Enarthrosis) .  Articular  sur- 
faces: head  of  the  femur,  and  the  acetabulum  deepened  by  the 
glenoid  rim  of  the  acetabulum  (a  rim  of  nbro-cartilage).  The 
bones  are  directly  connected  by  the  ligamentum  teres  (or  round 
ligament)  within  the  joint,  which  is  attached  by  one  extremity  near 
the  middle  of  the  head,  and  by  the  other  to  the  bottom  of  the 
acetabulum  (Fig.  65). 

A  capsule  encloses  the  joint.  It  is  strengthened  by  special 
bands  of  fibers  extending  to  surrounding  bones — one,  the  ilio- 
femoral  from  the  ilium  to  the  great  trochanter,  resembles  an  in- 
verted letter  Y,  and  was  formerly  called  the  Y-ligament  (also  the 
ligament  of  Bigelow).  The  synovial  membrane  not  only  lines  the 
capsule  but  invests  the  ligamentum  teres. 

Motions. — Free  motion  in  every  direction,  like  that  of  the 
shoulder. 

Knee-joint  (hinge  or  ginglymus  joint)  (Fig.  66). — Articular 
surfaces:  the  condyles  of  the  femur,  the  head  of  the  tibia,  and  the 
posterior  surface  of  the  patella.  The  two  surfaces  on  the  top  of 
the  tibia  are  shallow,  but  their  depth  is  increased  by  semilunar 
fibro-cartilages  attached  around  the  borders,  thus  forming  shallow 
cups  for  the  condyles. 

The  femur  and  tibia  are  directly  connected  by  two  ligaments 
within  the  joint,  which  cross  each  other  and  are  therefore  called 
the  crucial  ligaments.  (One  passes  from  the  front  of  the  spine  to 
the  lateral  condyle,  the  other  passes  from  behind  the  spine  to  the 
medial  condyle.)  The  patella  lies  in  front  of  the  condyles,  being 
imbedded  in  a  thick  tendinous  band  about  three  inches  long  which 
continues  to  the  tuberosity  of  the  tibia.  (This  band  is  really  the 
tendon  of  insertion  for  some  thigh  muscles,  and  is  improperly 
called  the  ligament  of  the  patella.}  It  serves  as  the  anterior  liga- 
ment of  the  joint  but  is  at  the  same  time  the  quadriceps  extensor 
tendon,  sometimes  called  the  patellar  tendon.  There  are  distinct 


KNEE-JOINT  71 

medial  and  lateral  ligaments,  and  some  strong  oblique  bands  at  the 
back;  and  all  are  connected  by  a  capsule  which  encloses  the  joint 
cavity. 

The  synovial  membrane  is  very  extensive  (Fig.  66) ;  it  covers 
the  crucial  ligaments  and  semilunar  cartilages. 

Motions. — Flexion,  extension,  and  very  limited  rotation  of  the 
leg. 

Note. — The  patella  cannot  be  drawn  upward  under  any  circumstances. 
When  the  knee  is  flexed,  it  lies  against  the  lower  ends  of  the  condyles,  and  in 
kneeling  the  condyles  rest  upon  it.  The  elasticity  of  the  great  muscles  to 


Extension  of  synovial  sac  of  knee 
upon  femur 


Tendon  of  quadriceps  extensor, 
forming  fibrous  capsule  of  joint 


Patella 

-  Pre-patellar  bursa 
Condyle  of  femur  (inner) 
Ligamentum  mucosum 


Fatty  tissue 


Synovial  membrane  re- 
flected off  crucial  liga- 
ments 

Cut  end  of  anterior  cru- 
cial ligament 
Posterior  crucial  liga- 
ment 


Fatty  tissue  between 
ligamentum  patellae 
and  synovial  sac 


Bursa  beneath  ligamentum 
patellae 


Tibia 


FIG.  66. — INTERIOR  OF  KNEE-JOINT. — (Morris.) 


which  the  patellar  tendon  belongs,  allows  very  free  motion  and  at  the  same 
time  keeps  the  patella  always  in  place  close  to  the  condyles. 

Bursse. — There  are  several  small  cavities  called  bursse,  the  use  of  which  is 
to  prevent  friction  in  the  tissue  outside  the  knee-joint.  They  usually  com- 
municate with  the  joint.  The  largest  one  is,  however,  subcutaneous,  being 
in  front  of  the  patella  between  it  and  the  skin.  (Fig.  66  and  page  82.) 


72  ANATOMY   AND   PHYSIOLOGY 

Surgical  note. — This  prepatellar  burs  a  is  subject  to  frequent 
pressure  and  easily  becomes  inflamed  and  enlarged,  making  the 
so-called  "housemaid's  knee." 

Ankle-joint  (Hinge- j oin t) . — Articular  surfaces  on  the  medial 
and  lateral  malleoli  and  the  body  of  the  talus.  They  are  connected 
by  anterior,  posterior,  and  lateral  ligaments. 

The  medial  is  often  called  the  deltoid  ligament,  from  its  shape  A  like  the 
Greek  letter  delta,  and  the  lateral  ligament  is  in  three  distinct  bands,  the 
anterior ',  middle,  and  posterior. 

Motions. — Flexion,  extension,  and  slight  abduction  and  adduc- 

\\ 


Medial  or 
deltoid 
ligament 


Plantar  ligaments 

FIG.  67. — LIGAMENTS  OF  THE  ANKLE-JOINT  AND  PLANTAR  REGION. — (Morris.} 

tion;  also  lifting  the  medial  border,  or  eversion,  and  lifting  the 
lateral  border,  or  inversion. 

Notes.— The  trans-verse  ligament  is  a  special  band  behind  the  talus,  connect- 
ing the  two  malleoli,  to  prevent  backward  dislocation  of  the  foot  in  jumping, 
running,  etc. 

There  is  no  motion  of  the  lower  extremity  which  corresponds  to  supination 
in  the  upper,  the  whole  extremity  being  in  the  permanently  pronated  position, 
which  brings  the  great  toe  toward  the  median  line  of  the  body,  or  on  the 
medial  border  of  the  foot.  (The  thumb  is  on  the  lateral  border  of  the  hand.) 

Tarsal  joints. — An  inter  osseous  ligament  connects  the  talus  to  the 
calcaneus;  it  is  the  strongest  one  in  the  body.  Short  fibrous  bands 


ARCHES    OF    THE    FOOT 


73 


connect  the  various  tarsal  bones  to  each  other  to  complete  the 
instep,  and  there  is  one  elastic  ligament  upon  which  the  head  of  the 
talus  rests.  It  assists  to  prevent  excessive  jarring  as  the  foot 
strikes  the  ground.  (This  is  the  only  ligament  containing  elastic 
tissue  in  the  extremities.) 

Metatarsal. — Like  the  metacarpal,  except  that  the  heads  are 
all  joined  together  by  a  transverse  band;  the  great  toe  is  not  free. 

Phalangeal. — Like  those  of  the  hand. 

Arches  of  the  foot. — The  principal  arch  is  from  the  heel  to 
the  ball  of  the  foot;  a  second  one,  the  transverse,  is  equally  im- 


Tendo  Achillia 
Talus  Vessels  and  nerve 


Scaphoid 
First  cuneiform 


First  metatarsal 


Calcaneus 


Muscles  of  plartar  region 

FIG.  68. — MEDIAL  BORDER  OF  RIGHT  FOOT,  SHOWING  BONES  IN  POSITION. — (Morris.} 

portant.  The  arteries  and  nerves  in  the  sole  of  the  foot  are  pro- 
tected from  pressure  by  these  arches,  which  are  preserved  not 
only  by  the  ligaments  and  the  shape  of  the  bones,  but  by  the 
tendons  of  certain  muscles. 

Practical  points. — In  walking  the  weight  is  transmitted  principally  through 
the  talus,  the  navicular,  and  three  cuneiform  bones  to  the  three  medial  toes, 
giving  the  "springy"  step  to  the  well-arched  foot.  In  standing,  it  falls  more 
upon  the  calcaneus,  and  is  distributed  through  the  cuboid  to  the  two  lateral 
toes  as  well. 


RESUME 

Comparing  the  joints  in  the  upper  and  lower  extremities,  note 
that   both  the  shoulder  and  hip  are  ball-and-socket  joints;  that 


74  ANATOMY   AND    PHYSIOLOGY 

the  elbow  and  knee  are  hinge-joints,  as  are  also  the  wrist  and 
ankle;  but  whereas  in  the  wrist  extension  is  limited,  in  the  ankle 
it  is  so  free  as  to  bend  the  top  of  the  foot  almost  against  the  leg, 
becoming  dorsal  flexion,  and  is  actually  called  flexion  of  the  ankle- 
joint,  the  term  extension  being  used  to  signify  the  act  of  straighten- 
ing the  foot  in  a  line  with  the  leg. 

The  back  of  the  hand  and  the  top  of  the  foot  are  both  called 
the  dorsum;  the  face  of  the  hand  is  the  palm  or  volar  surface,  and 
the  sole  of  the  foot  is  the  plantar  surface.  The  thumb  is  free;  the 
great  toe  is  bound  with  the  others. 

The  following  table  of  articular  nerves  is  inserted  in  this  place 
for  convenient  reference,  when,  in  the  care  of  painful  joint  affec- 
tions, the  nurse  may  be  interested  to  know  the  names  of  the  par- 
ticular nerves  involved. 

NERVE  SUPPLY  TO  THE  PRINCIPAL  JOINTS 

Temporo-mandibular. . .  Fifth  cranial  or  trifacial. 

Shoulder Suprascapular,  subscapular,  axillary. 

Elbow Musculo-cutaneous  (principally). 

Wrist  and  hand Ulnar,  median,  deep  branch  of  radial. 

Joints  of  spinal  column.  Spinal  nerves. 

Hip Femoral,  obturators,  sciatic. 

Knee Femoral,  obturator,  tibial,  peroneal. 

Ankle  and  foot Deep  branch  of  peroneal,  two  plantar  nerves. 


CHAPTER  V 
COMPLETION,  REPAIR  AND  FUNCTIONS  OF  BONES 

NOTES  CONCERNING  THE  COMPLETION  OF  LONG  BONES 

In  the  humerus,  radius,  and  ulna,  the  nutrient  canals  lead  toward  the  elbow 
and  the  bones  are  completed  here  at  an  earlier  date  than  at  the  wrist  or 
shoulder.  In  the  femur,  tibia,  and  fibula,  the  nutrient  canals  lead  away 
from  the  knee;  and  the  bones  are  completed  first  at  the  hip  and  the  ankle. 

Surgical  notes. — The  time  of  union  of  the  extremities  and  shafts  of  long 
bones  is  important  from  a  surgical  viewpoint.  Thus,  in  the  ends  of  bones 
at  the  elbow-joint  the  extremities  join  the  shafts  at  about  the  seventeenth  or 
eighteenth  year;  therefore,  injuries  near  the  elbow-joint  before  this  age  may 
cause  a  separation  of  the  parts,  called  an  epiphyseal  fracture.  The  upper 
end  of  the  humerus  and  lower  ends  of  the  radius  and  ulna  unite  with  their 
shafts  at  about  the  twentieth  year;  therefore,  in  the  case  of  an  injury  of  the 
shoulder  or  wrist  before  this  age  the  same  possibility  is  borne  in  mind. 

In  the  lower  extremity  certain  differences  are  noted,  since  the  nutrient 
arteries  run  differently.  The  bones  are  completed  first  at  the  upper  end  of  the 
thigh,  at  about  nineteen,  and  at  the  lower  end  of  the  leg  at  about  eighteen  or 
twenty  years,  while  the  knee  is  completed  last,  at  between  twenty  and 
twenty-five. 

,  It  is  important  for  the  nurse  to  understand  something  of  the 
nature  of  the  baby's  skeleton.  The  general  condition  at  certain 
periods  of  life  is  also  of  interest. 

BRIEF  SURVEY  OF  THE  SKELETON  AT  DIFFERENT  AGES 

At  birth:— 

Head. Skull-bones  have  unossified  borders  and  angles,  there- 
fore, the  membrane  is  soft  at  the  fontanelles;  the  base 
of  the  skull  is  largely  in  cartilage,  and  the  bones  are 
slightly  movable. 

Face-bones  small  and  very  incomplete. 

Spinal  column Bodies  of  vertebrae  partially  ossified,  with  much  carti- 
lage between  them. 
Arches,  each  in  two  separate  pieces  or  halves. 

Pelvic-girdle Hip-bones  (ossa  coxae)  in  three  pieces,  well  separated 

by  cartilage. 

Sacrum  partially  ossified. 
Coccyx  not  at  all  ossified. 
Ribs Shafts  only  are  bony. 

75 


76  ANATOMY  AND   PHYSIOLOGY 

Sternum Presents  a  number  of  small  centers,  imbedded  in  cartil- 

lage. 

Upper  extremity Shoulder-girdle  ossified  at  acromial  end  of  clavicula  and 

in  body  of  scapula;  other  parts  are  cartilage. 
Long  bones — Shafts  partially  ossified. 
Carpus — all  bones  entirely  cartilaginous. 

Lower  extremity  .. .  Long  bones — Shafts  partially  ossified;  at  the  knee  the 

ends  of  the  femur  and  the  tibia  have  begun  to  ossify. 

Tarsus — three  bones  (talus,  calcaneus,  and  cuboideum) 

have  begun  to  ossify. 
The  metacarpal,  metatarsal  and  phalangeal  bones  have 

thin  lines  of  osseous  tissue  before  birth. 
At  age  of  20  years 
Head 


Hands 


All  completed. 


Feet 

Long  bones All  completed  except  tibia  and  fibula  whose  upper  ends 

are  not  yet  united  with  the  shafts. 

Ribs          1 

0,  \ Are  in  two  pieces  each. 

Sternum    j 

Shoulder-girdle Clavicula,  sternal  end  still  separate.     Scapula  soft  at 

borders  and  processes. 
Pelvic-girdle Hip-bones  (ossa  coxae)  completed.     Sacrum  and  coccyx 

still  in  two  or  more  pieces. 

Spinal  column All  parts  ossified. 

At  age  of  25  years:.  The  skeleton  is  practically  completed.     The  bones  are 

strong,  and  the  proper  proportions  of  animal  and 

mineral  matter  are  preserved  during  adult  life. 
The  coccyx  may  unite  with  the  sacrum  in  middle  life, 

thus  modifying  one  of  the  diameters  of  the  pelvic 

outlet. 
In  old  age: There  is   no   more   growth.     The   supply   of   animal 

matter  decreases,  and  the  bones  become  brittle  so 

that  they  may  be  easily  broken. 

POINTS  OF  PRACTICAL  INTEREST  CONCERNING  THE  BONES  IN 

INFANCY 

First,  the  baby's  bones  are  soft,  and  are  still  largely  composed 
of  cartilage.  Second,  since  the  process  of  ossification  is  going  on 
continually,  the  proper  shape  of  the  cartilage  should  be  preserved 
in  order  that  the  shape  of  the  future  bone  may  be  normal.  In 
infancy  the  skull  bones  are  movable  as  well  as  soft,  and  the  shape  of 
the  baby's  head  may  be  altered  by  pressure.  Witness  the  Flathead 
Indians,  who  bind  a  board  across  the  top  of  the  infant's  skull. 


REPAIR   OF  BONE  77 

The  spine  and  the  vertebral  extremities  of  the  ribs  are  com- 
posed largely  of  cartilage;  it  is  therefore  evident  that  not  only 
should  a  young  baby's  back  be  supported,  but  the  child  should 
rest  in  a  horizontal  position,  the  spine  being  so  soft  that  it  cannot 
easily  be  held  upright,  even  if  the  little  muscles  were  strong 
enough  to  do  this  without  fatigue. 

The  pelvis  and  hip. — During  the  first  year  or  two  both  the 
sacrum  and  the  coccyx  are  still  in  separate  pieces,  while  the  centers 
in  the  three  portions  of  the  hip-bones  are  well  separated  by  cartil- 
age, leaving  the  acetabulum  unossified;  the  head  of  the  femur  is  also 
soft.  Consequently,  a  thought  only  is  needed  to  explain  why  the 
clothing  about  a  baby's  hips  should  leave  them  free  from  pressure. 

Note.- — An  advantage  is  derived  from  the  softness  of  the 
skeleton  during  childhood,  as  the  many  jarrings  and  tumbles 
incident  to  the  child's  experience  are  far  less  injurious  to  the  jelly- 
like  frame  than  they  would  be  to  a  harder  one. 

Green-stick  fracture.- — Up  to  the  age  of  four  years  the  bones 
are  sufficiently  soft  to  bend  rather  than  break,  as  an  older  bone 
would  do  under  similar  circumstances.  Usually  some  of  the 
fibers  do  break,  but  not  the  whole  bone;  this  is  called  a  green- 
stick  fracture,  because  the  bone  behaves  like  a  bough  of  green 
wood  when  forcibly  bent. 

Rachitis  or  rickets. — In  this  disease  ossification  is  delayed, 
and  the  bones  are  more  soft  and  yielding  than  usual  until  com- 
pletely ossified.  The  extremities  grow  larger  and  the  shafts  are 
often  bent.  When  the  mineral  salts  are  finally  deposited  the  bone 
is  permanently  misshapen.  Rachitis  is  a  disease  of  malnutrition 
from  deficiency  of  mineral  food. 

Spina  bifida. — In  the  formation  of  the  vertebrae,  the  comple- 
tion of  the  arches  and  spinous  processes  occurs  latest  in  the  lower 
lumbar  and  upper  sacral  region.  Sometimes  it  is  not  perfect,  and 
the  spinal  canal  is  then  left  open.  This  condition  is  known  as 
spina  bifida  and  the  membranes  and  fluid  of  the  spinal  cord  pro- 
trude, forming  a  tumor  upon  the  child's  back.  Spina  bifida 
occurs  rarely  in  other  regions. 

REPAIR  OF  BONE 

When  a  bone  is  broken  nature  repairs  it  in  her  own  way. 
First,  more  blood  flows  to  the  part;  then  a  certain  amount  of 


78  ANATOMY   AND   PHYSIOLOGY 

animal  matter  like  cartilage,  appears  about  the  fracture,  forming 
a  callus.  This  is  soon  hardened  by  deposit  of  mineral  matter  and 
the  callus  becomes  bone,  but  the  mark  of  fracture  and  repair  will 
always  remain.  The  callus  will  form  and  unite  the  ends  of  bone 
even  if  they  are  not  well  matched,  but  in  this  case  deformity  will 
result.  If  the  callus  does  not  harden  the  union  is  fibrous. 

Surgical  note. — "  Setting"  a  fractured  bone  consists  in  placing 
the  ends  in  proper  position,  or  "apposition."  This,  nature  can- 
not do,  because  the  muscles  above  and  below  are  pulling  them 
out  of  place,  therefore  the  skill  of  the  surgeon  is  required  for  its 
accomplishment. 

Practical  point. — The  nursing  care  of  a  fracture  is  directed  to 
the  end  of  keeping  the  bone  supported  in  position,  and  as  far  as 
may  be,  perfectly  quiet  until  the  callus  is  hardened,  so  that  the 
least  possible  deformity  will  remain.  To  accomplish  this  the 
nurse  must  not  only  have  a  knowledge  of  anatomy,  but  must 
exercise  skill  and  judgment  to  an  unusual  degree. 

PHYSIOLOGY  OF  BONE  AND  THE  SKELETON 

At  first  thought  it  would  appear  that  not  much  could  be  said 
concerning  the  physiology  of  bone  tissue,  which  is  a  finished  prod- 
uct, the  changes  which  it  undergoes  being  directed  solely  to  its 
own  preservation.  The  ability  of  bone  to  repair  injuries  by  utiliz- 
ing material  from  the  blood  is,  however,  a  physiologic  process; 
and  the  membranes  which  cover  bony  surfaces  (periosteum 
outside,  endosteum  within  medullary  canals)  have  a  well-defined 
function  in  the  formation  of  bone  tissues,  already  referred  to. 
One  of  the  most  important  functions  of  the  body,  namely: — pro- 
viding an  origin  for  cells  (or  corpuscles)  of  the  blood,  belongs  to  the 
marrow  of  bones.  Cancellous  bone  contains  in  its  spaces  thin  red 
marrow  (the  "red  bone  marrow"  of  clinic  use)  in  which  red  cells 
have  their  origin,  while  the  medullary  canals  of  long  bones  contain 
a  firmer  fatty  marrow  where  many  of  the  white  cells  of  the  blood 
have  their  beginning. 

Taking  a  broad  view,  we  find  many  points  of  interest  in  the 
bones  and  the  skeleton  which  they  comprise,  some  of  which  have 
already  been  touched  upon.  It  is  their  mechanical  physiology 
which  is  conspicuous  and  of  great  importance — they  afford  attach- 
ment to  muscles;  they  enclose  cavities;  they  sustain  pressure. 


THE   ARTICULATED   SKELETON  79 

Their  usefulness  is  due  to  their  physical  characteristics — for  in- 
stance, the  hardness  of  bones  enables  the  framework  which  they  com- 
pose to  support  the  soft  parts  of  the  body,  and  in  certain  localities 
enables  them  to  protect  internal  organs.  An  important  example 
is  the  neural  canal  with  its  contents- — the  brain  and  spinal  cord. 

Again,  it  is  this  same  quality  of  hardness  which  enables  the  skel- 
eton to  bear  direct  pressure  and  the  body  weight.  Osseous  tissue 
in  certain  bones — notably  the  femur  and  the  os  coxae — is  especially 
arranged  in  lines  of  pressure  for  this  purpose;  namely,  that  super- 
imposed weight  may  be  borne  with  the  least  strain  upon  the  bone. 

The  relation  between  the  shapes  of  bones  and  the  arrangement 
of  their  two  tissues  has  a  direct  bearing  upon  their  usefulness  and 
the  convenience  with  which  it  is  exercised.  Examples  are  seen 
in  the  long  bones- — their  (comparatively)  large  extremities  enter 
into  the  formation  of  joints;  they  also  give  attachment  to  many 
muscles  which  move  the  joints.  Here,  extent  of  surface  is  needed 
and  cancellous  bone  is  used  with  but  a  thin  covering  of  compact, 
thus  securing  the  necessary  surface  without  undue  weight.  Their 
shafts  give  attachment  to  fewer  muscles,  but  their  position  in  the 
extremity  exposes  them  to  violence  (applied  transversely)  and 
calls  for  endurance  of  strain.  Hence,  for  these  two  reasons — first, 
that  extent  of  surface  is  unnecessary;  and  second,  that  strength 
and  endurance  are  demanded- — the  compact  tissue  is  appropriate. 
It  also  secures  a  convenient  slenderness  of  bone  where  the  bulk  of 
muscle  tissue  is  greatest. 

By  far  the  greatest  variety  of  functions  is  seen  in  the  articu- 
lated skeleton,  whereby  the  movements  necessary  to  the  well-being 
of  the  individual  are  made  possible  by  the  character  of  the  joints. 

The  movements  of  the  trunk  are  limited,  but  sufficient  for  the 
needs  of  the  organs  which  it  contains;  while  those  of  the  extremities 
are  many  and  free.  They  may  resist  external  force;  they  may 
themselves  overcome  opposing  forces.  They  may  be  used  as 
weapons  of  offense  or  defense.  Facilities  for  transporting  the  body 
from  place  to  place,  or  locomotion,  are  provided  by  the  articulated 
bones  of  the  lower  extremities;  and  the  power  of  the  upper  ex- 
tremities to  perform  a  thousand  necessary  acts  would  not  exist 
without  a  similar  framework.  These  points  have  been  mentioned 
already,  and  will  be  dwelt  upon  later  in  connection  with  the  study 
of  the  muscular  system. 


CHAPTER  VI 

THE*  CONNECTIVE  TISSUE  FRAMEWORK  AND  THE 
SKELETAL  MUSCLE  SYSTEM 

THE  FASCLE  OF   THE   BODY  AND  MUSCLES  OF  THE 
HEAD  AND  TRUNK 

Although  present  in  every  part  of  the  body,  the  connective 
tissue  is  so  conspicuously  associated  with  the  muscle  system  that 
a  few  facts  of  interest  concerning  this  universal  tissue  are  here 
reviewed,  before  commencing  the  study  of  the  muscles. 

For  muscles  it  is  a  veritable -framework,  as  will  be  seen.  In 
fibrous  form  it  is  conspicuous  on  their  surfaces  as  sheaths,  or  as 
separating  one  from  another;  and  in  tendons.  As  delicate  areolar 
tissue  it  invades  them,  bearing  tiny  vessels  and  nerves  and  forming 
tissue-spaces. 

This  it  does  in  all  organs — wrapping  them,  supporting  their 
cells,  and  invading  them  to  convey  vessels  and  nerves.  It  fills  in 
spaces  between  organs,  and  accompanies  large  vessels  to  and  from 
them.  It  connects  organs  to  each  other;  and  everywhere  it  forms 
a  network  of  tissue-spaces  containing  nutritive  fluid  obtained  from 
the  blood-vessels  for  the  cells  of  the  body. 

If  one  could  imagine  that  everything  in  the  human  body  ex- 
cept connective  tissue  could  be  destroyed,  the  remaining  portion 
would  bear  the  same  relation  to  the  body  that  had  been,  as  a 
skeleton  leaf  bears  to  a  fresh  green  one. 

THE  FASCIAE  OF  THE  BODY 

The  word  fascia  is  applied  to  the  connective  tissue  which 
surrounds  various  organs  or  lines  cavities.  Fascia  is  found  in 
every  part  of  the  body,  and  we  shall  study  here  two  varieties,  which 
are  associated  with  the  muscles  and  skin.  They  are  called  the 
deep  and  the  superficial  fascia. 

The  deep  fascia. — This  is  a  firm  layer  of  connective  tissue 
with  but  small  spaces  between  its  fibers,  therefore  it  is  dense  and 

80 


DEEP   FASCIA 


8l 


tough.  It  is  white  and  smooth,  and 
seldom  contains  any  fat.  The  deep 
fascia  covers  the  muscles  and  binds 
them  down,  and  also  separates  them 
into  groups,  thus  forming  intermus- 
cular  septa.  (Many  muscle  fibers 
arise  from  intermuscular  septa.) 

Special  points. — The  inguinal 
ligament  (Fig.  79)  is  a  band  of  the 
deep  fascia  between  the  spine  of  the 
ilium  and  the  tubercle  of  the  pubes. 
It  feels  like  a  cord  from  one  bone  to 
the  other. 

The  fascia  lata  (broad  fascia)  is  that 


Great  or 
long  saph- 


FIG.  69.— DEEP  FASCIA  OF  THIGH  FIG.  70.— SHOWING  OVAL  FOSSA. 
(Partial).  6,  7,  8,  10,  14,  indicate  por-  The  superficial  fascia  has  been  dissected 
tions  of  fascia  lata. — (Sappey.)  away,  leaving  cutaneous  veins  lying 

upon  deep  fascia. 

portion  of  the  deep  fascia  which  covers  the  muscles  of  the  thigh;  it  is  thicker 
and  stronger  than  any  other  fascia  of  the  body.    It  is  attached  to  the  hip- 
bones above  and  the  leg-bones  below.     A  portion  which  is  especially  tense 
6 


82  ANATOMY   AND   PHYSIOLOGY 

and  strong  may  be  felt  on  the  lateral  side  of  the  thigh,  above  the  tuberosity 
of  the  femur,  like  a  tight  band  attached  to  the  tibia;  it  is  called  the  ilio-tibial 
band.  See  page  113,  tensor  fascice  latce. 

The  oval  fossa  or  saphenous  opening  (Fig  70)  in  the  fascia 
lata  is  an  inch  and  a  half  below  the  medial  portion  of  the  inguinal 
ligament.  It  allows  the  long  saphena  vein  to  pass  through  to  the 
femoral  vein. 

The  lumbar  fascia  is  not  a  part  of  the  general  deep  fascia  of  the  body, 
but  belongs  to  the  transversus  muscle  described  on  p.  96.  It  is  attached 
behind  to  the  lumbar  vertebra,  above  to  the  last  two  ribs,  and  below  to  the 
crest  of  the  ilium. 

The  superficial  fascia  covers  the  deep  fascia.  It  lies  immedi- 
ately beneath  the  skin  in  its  whole  extent  and  consists  of  loose- 
meshed  connective  tissue,  arranged  somewhat  in  layers,  and  con- 
taining the  subcutaneous  fat.  It  also  imbeds  the  superficial  or 
cutaneous  arteries,  veins,  and  nerves  between  its  layers.  In 
places  where  the  fascia  is  thin,  as  on  the  back  of  the  hand,  the 
veins  are  easily  seen.  This  fascia  is  closely  connected  with  the 
skin,  and  they  glide  together  over  the  deeper  structures. 

A  bursa  is  a  sac  in  the  fascia  which  contains  smooth  fluid 
resembling  synovia.  Burs<z  are  found  where  much  pressure  or 
friction  occurs  between  different  structures.  They  act  like 
water- cushions,  thus  saving  the  tissues  from  bruising  or  rubbing. 
The  largest  subcutaneous  bursa  is  in  the  superficial  fascia  in  front 
of  the  patella.  It  is  called  the  prepatellar  bursa  (Fig.  66). 

Surgical  note. — When  the  prepatellar  bursa  becomes  in- 
flamed and  enlarged,  it  forms  "housemaid's  knee." 

Sometimes  bursae  are  placed  underneath  tendons  or  between 
muscles,  and  these  deep  ones  may  communicate  with  joints. 
There  is  a  large  one  between  the  gluteus  maximus  and  the  tuber- 
osity of  the  ischium,  and  another  between  the  same  muscle  and 
the  great  trochanter. 

Note. — The  transversalis  and  pelvic  fasciae  are  found  within  the  abdomen 
and  the  pelvis,  respectively  (see  pages  100  and  in). 

MUSCLES,  THEIR  IMPORTANCE 

The  growth  of  bone  and  fashioning  of  joints  has  but  prepared 
the  way  for  more  important  ends  to  be  accomplished. 

The  head  and  trunk  protect  and  support  the  vital  organs,  but 


MUSCLE   STRUCTURE  83 

the  food  and  the  air  upon  which  their  life  depends  come  only 
through  the  aid  of  those  constant  workers,  the  muscles.  All 
motion  of  any  sort  in  the  body,  whether  conscious  or  unconscious, 
is  due  to  their  action.  If  the  motion  is  voluntary  it  is  due  to 
muscles  which  are  controlled  by  the  will,  or  voluntary  muscles. 
Muscles  which  cannot  be  controlled  by  the  will  are  involuntary; 
they  are  found  in  the  internal  organs  of  the  body,  or  the  viscera, 
and  in  the  coats  of  vessels.  All  other  muscles  are  voluntary,  and 
since  they  are  attached  to  bones  they  are  called  skeletal  muscles. 

Contractile  tissues: — Muscular  and  ciliated  epithelial  cells. 
Striped  skeletal  muscle. 
Striped  cardiac  muscle. 
Unstriped  visceral  muscle. 

STRUCTURE   OF  MUSCLES 

Muscles  consist  chiefly  of  collections  of  red  fibers,  each  fiber 
composed  of  little  bundles  of  muscle-cells.  All  of  these  are 
wfappecTin  connective  tissue,  bound  together  and  enclosed  in  a 
sheath. 

Transition  zone. 


FIG.  71.— LONGITUDINAL  SECTION  OF  A  PART  OF  A  MUSCLE  FIBER  FROM.  A 
HUMAN  INTERNAL  INTERCOSTAL  MUSCLE,  SHOWING  ITS  TRANSITION  TO  TENDON. 
X  750. — (Lewis  and  Stohr.) 

Examining  a  muscle  with  care,  we  can  strip  off  the  sheath  of  connective 
tissue  (epi-mysium) ,  and  we  shall  find  that  it  sends  layers  down  into  the 
muscle  to  form  septa  or  partitions  (peri-mysium)  enclosing  the  bundles  (or 
fasciculi)  of  which  the  muscle  is  made  up. 

With  the  aid  of  the  microscope  the  fiber  cells  which  compose  the  bundles 
are  revealed,  surrounded  by  still  more  delicate  connective  tissue  (endo- 
mysium) . 

Also,  under  the  microscope  the  fiber  cells  of  voluntary  muscle  tissue  ap- 
pear striped,  consequently  voluntary  muscle  is  said  to  be  striped  or  striated. 
Involuntary  fiber  cells  are  plain — involuntary  muscle  is  unstriped  or  non- 
striated.  This  sort  of  muscle  is  found  in  internal  organs,  whose  work  must  go 
on  continually  without  our  conscious  supervision. 


84 


ANATOMY   AND    PHYSIOLOGY 


Exception. — The  heart :  which  acts  whether  we  will  or  not,  although  its 
muscle  is  striated. 

In  most  cases  the  connective  tissue  is  prolonged  beyond  the 
muscle  into  a  white  cord  or  band  called  a  tendon,  if  the  muscle  is 
long  and  thick;  or  into  a  broad  thin  layer  called  an  aponeurosis  if 
the  muscle  is  flat;  and  by  these  tendons  and  aponeuroses  the 


FIG.  72. — SHOWING  EXTREMITIES  OF 
MUSCLES.  2,  Tendon.  5,  Aponeuro- 
sis.— (Sappey.) 


FIG.  73. — INTERCOSTAL   MUSCLES. — 
(Morris.} 


muscles  are  attached  to  bones  and  other  organs.  Sometimes  the 
red  fibers  are  attached  directly  to  the  parts  which  they  move,  but 
in  by  far  the  greater  number  the  tendons  are  conspicuous  (Fg.  72). 
Muscles  are  described  as  consisting  of  a  body  and  two  ex- 
tremities; the  body  or  belly  being  the  red  contracting  part  which 
swells  in  action,  while  tendons  (which  are  possessed  by  most  of  the 


INTERCOSTAL   MUSCLES  85 

muscles)  are  simply  strong  white  fibrous  bands  having  no  power  to 
contract  and  no  elasticity.     This  is  equally  true  of  the  aponeuroses. 

The  attachments  of  the  extremities  are  spoken  of  as  the  origin 
and  the  insertion.  The  extremity  which  is  stationary  while  the 
other  end  moves,  is  the  origin;  the  end  which  moves  with  the 
organ  attached  to  it,  is  the  insertion. 
The  insertion  is  always  pulled  toward  the 
origin  when  the  muscle  contracts. 

The  names  of  muscles  are  not  applied 
according  to  a  uniform  plan,  being  some- 
times chosen  because  of  location,  as  the 
intercostals  (between  ribs)  or  the  epicranial 
muscle  (upon  the  head),  etc;  or,  the  shape 
may  determine  the  name,  as  orbicularis 
oris  (ring  muscle  of  the  mouth) ;  but  of  tenest 
the  name  signifies  the  action  of  the  muscle. 
The  original  names  are  in  the  Latin  tongue 
but  the  English  translation  is  often  used. 
The  full  Latin  name  includes  the  word 
musculus  (muscle)  which  is  quite  com- 
monly omitted  for  the  sake  of  brevity. 

SKELETAL  MUSCLES  OF  THE  TRUNK1 

Intercostal  muscles. — In  two  sets,  the 

internal  and  the   external,  which  occupy 
the   intercostal    spaces.     The    fibers  run 

obliquely    from    rib  to    rib,   the   internal 

,         ,    .  FIG.    74.— THE  FIGURES 

fibers   running  upward  and  forward,  the  REFER  TO  THE  SPINAL  GROUP 


external    fibers     running    downward    «»*  *£^(&I ^5 

forward.     (Fig.  73.) 

Action. — They  move  the  ribs  up  and  down  in  breathing  and 
the  various  acts  associated  with  it. 

PRINCIPAL  MUSCLES  OF  THE  BACK 

In  the  skeleton  a  broa^i  groove  exists  on  either  side  of  the 
spinous  processes,  which  is  filled  in  its  whole  extent  with  many 
vertical  muscles  of  different  lengths,  the  use  of  which  'is  to  hold 

1  Many  skeletal  muscles  have  their  origin  partly  from  the  deep  fascia  covering 
them.  The  bony  origins  alone  are  given  here,  as  a  rule  and  only  the  more  important 
of  those. 


86  ANATOMY  AND   PHYSIOLOGY 

the  spine  in  the  erect  position;  also  they  assist  to  move  it  in 
various  directions. 

The  erector  spinae  is  the  name  given  to  this  large  group, 
which  is  bound  down  in  its  place  by  a  thin  layer  of  fibrous  tissue 
called  the  vertebral  aponeurosis.  This  muscle  group  extends  from 
the  skull  to  the  lower  part  of  the  sacrum  (Fig.  74) . 

The  action  is  most  easily  seen  in  the  lumbar  and  dorsal  regions? 
where  it  is  not  deeply  covered  with  other  muscles. 

Nerves. — Posterior  spinal. 

The  latissimus  dorsi  (broadest  of  the  back,  Fig.  75). — This 
muscle  covers  most  of  the  erector  spinae  and  a  great  portion  of 
the  back  of  the  trunk. 

Origin. — The  spinous  processes,  from  the  sixth  thoracic  down 
to  the  end  of  the  column.  (Also  the  crest  of  the  ilium  and  a  few 
fibers  from  the  inferior  angle  of  the  scapula.)  Insertion. — The 
crest  of  the  lesser  tubercle  of  the  humerus. 

Action. — Principally  to  pull  the  arm  backward  and  keep  the 
scapula  or  shoulder-blade  close  to  the  chest;  brought  prominently 
into  use  in  rowing  a  boat  or  when  the  body  is  suspended  by  the 
hands  and  an  effort  is  made  to  draw  it  up. 

Nerves. — Posterior  spinal  and  long  subscapular. 

MUSCLES  OF  THE  BACK  OF  THE  NECK 

These  muscles  move  the  head  and  neck.  Only  the  most 
important  are  here  described. 

The  splenius. — This  muscle  is  in  two  portions,  the  splenius  of  the  head 
(capitis)  and  the  splenius  of  the  neck  (cervicis) . 

Origin. — The  spinous  processes  of  the  last  cervical  and  first  six  thoracic 
vertebrae.  Insertion. — Partly  upon  occipital  and  mastoid  bones  (splenius 
capitis)  and  partly  .upon  the  transverse  processes  of  the  upper  vertebrae 
(splenius  cervicis). 

Action. — The  muscle  of  one  side  alone  will  rotate  the  head,  twisting  the 
neck.  The  muscles  of  both  sides  acting  together  simply  pull  the  head  back- 
ward or  extend  it  and  the  neck. 

Nerves. —  Posterior  cervical. 

• 

The  trapezius  covers  the  other  muscles  of  the  back  of  the 
neck,  and  also  the  upper  portion  of  the  latissimus  dorsi.  It  is  one 
of  the  largest  muscles  in  the  body  (Fig.  75).  T^e  two  muscles, 
right  and  left  together  make  a  large  diamond-shaped  sheet. 


TRAPEZITS  87 

Origin. — The  occipital  bone,  the  ligamentum  nuchae,  and  the 
spinous  processes  of  the  thoracic  vertebras.  Insertion. — The  spine 
of  the  scapula  and  lateral  third  of  the  clavicula. 

Action. — With  the  shoulders  stationary  the  trapezius  acts  upon 
the  head  to  pull  it  backward  or  sideways.  With  the  head  station- 


FIG.  75. — SUPERFICIAL  AND  MIDDLK  MUSCULAR  LAYERS  o?  JHE  POSTERIOR  ASPECT 

OF  THE  TRUNK.— (Sappcy.) 

i,  Trapezius;  2,  latissimus  dorsi;  3,  aponeurosis;  4,  5,  6,  8,  19,  20,  different  por- 
tions of  latissimus  dorsi;  9-12,  deep  muscles;  13,  sterno-mastoid;  14,  splenius;  15, 
elevator  of  scapula;  16,  infraspinatus;  17,  teres  minor;  7,  18,  teres  major;  21,  portion 
of  anterior  serratus;  22,  23,  abdominal  muscles;  24,  25,  gluteus  maximus;  26-30, 
deep  muscles;  31,  deltoid;  32,  triceps. 

ary  it  can  elevate  the  shoulder-girdle  and  the  whole  upper  ex- 
tremity with  it.     Both  muscles  together  can  draw  the  shoulders 


88 


ANATOMY   AND   PHYSIOLOGY 


back.     If  the  hands  grasp  a  bar  above  the  head  these  muscles 
will  assist  to  draw  the  body  up.     The  largest  two  of L the  "  climbing 
muscles''  are  the  latissimus  dorsi  and  the  trapezius. 
Nerves. — Spinal  accessory  and  middle  cervical. 

Note. — Observe  in  the  illustration  its  tendinous  area,  which  remains  flat 
during  action  of  the  muscle. 


Fron  tails 


Ear  muscles 


Chin      / 
muscles 


Sterno-mastoid 


FIG.  76. — MUSCLES  or  THE  HEAD  AND  NECK. — (Morris.) 

Clinical  Note.- — Spasmodic  action  of  the  trapezius  is  often  the 
cause  of  wry-neck,  or  torticollis,  and  this  may  be  increased  by 
spasm  of  the  splenius. 


MUSCLES  OF  EXPRESSION  89 

MUSCLES  OF  HEAD,  AND  FRONT  AND  SIDE  OF  THE  NECK. 

The  muscles  of  expression  are  those  of  the  scalp  and  face. 
They  are  closely  connected  with  the  under  surface  of  the  skin,  or 
with  each  other;  they  have  no  deep  fascia  over  them,  and  there- 
fore their  slightest  contraction  is  shown  on  the  face,  thus  varying 
the  movements  and  lines  of  expression. 

Epicranial  muscle. — On  the  forehead  and  the  top  and  back 
of  the  head — a  broad  thin  muscle  made  up  of  two  distinct  parts 
with  an  aponeurosis  between  them.  The  posterior  part  is  the 
occipitalis,  taking  origin  from  the  curved  line  of  the  occipital 
bone  and  ending  in  the  aponeurosis  on  the  top  of  the  head.  The 
anterior  part  is  the  frontalis,  having  origin  in  the  aponeurosis, 
and  passing  down  over  the  forehead  to  the  insertion  in  the  tissues 
of  the  eyebrows. 

Action. — Principally  to  lift  the  eyebrows,  producing  the  trans- 
verse wrinkles  across  the  forehead  which  express  surprise.  The 
skin  is  closely  connected  with  this  double  muscle  so  that  the 
contraction  causes  movement  of  the  scalp.  (Some  people  can 
move  the  scalp  backward  and  forward  by  contracting  the  two 
portions  alternately.) 

The  aponeurosis  extends  in  a  thin  layer  at  the  side  over  the  temporal 
region,  giving  origin  to  certain  small  muscles  which  move  the  ear.  The  scalp 
and  ear  usually  move  together. 

Nerve. — Seventh  cranial  (or  facial}. 

Levator. palpebrae  (elevator  of  the  eyelid). — Within  the  orbit. 
Origin. — At  the  apex  of  the  orbit.    Insertion. — In  the  upper  lid. 
Action. — It  lifts  the  lid  and  opens  the  eye. 

Nerve. — Seventh  cranial.     See  page  343  for  other  Orb  tal  Muscles. 

Corrugator. — The  muscle  which  wrinkles  the  eyebrow. 
Origin. — The  frontal  bone.  Insertion. — The  under  surface  of 
eyebrow. 

Action. — It  draws  the  brows  downward  and  inward  toward 
each  other;  it  is  the  frowning  muscle. 

Nerve. — Seventh  cranial. 

Orbicularis  oculi. — The  ring-like  muscle  of  the  eyelid.  It  is 
attached  to  the  medial  border  of  the  orbit.  Some  of  its  fibers 
are  in  the  lid — the  palpebral  portion — while  others  surround  the 


go  ANATOMY  AND   PHYSIOLOGY 

lids  like  a  broad  flat  ribbon,  forming  the  circular  or  orbital  portion, 
and  bearing  the  eyebrows  (Fig.  76). 

Action. — When  the  palpebral  fibers  contract  the  lids  cover  the 
eyeballs  lightly;  when  the  circular  fibers  contract  the  lids  are 
pressed  against  the  ball. 

Nerve. — Seventh  cranial. 

Orbicularis  oris  (ring  muscle  of  the  mouth). — Surrounds  the 
opening  of  the  mouth,  constituting  the  larger  portion  of  the  lips. 
The  fibers  have  only  one  bony  attachment — on  the  maxilla,  below 
the  septum  of  the  nose. 

Action. — It  closes  the  mouth. 

The  lips  themselves  are  moved  in  various  ways  by  muscles 
above  and  below  them — the  elevators  and  depressors  of  the  lips 
(all  supplied  by  the  seventh  cranial  nerve). 

Special  points. — Most  of  the  changes  in  the  expression  of  the  face  are 
caused  by  the  action  of  the  ring  muscles  and  of  those  which  are  attached  to 
them.  For  example,  the  lifting  of  the  eyelids  by  the  frontalis  expresses  sur- 
prise. The  wrinkling  of  the  brows  by  the  corrugators  speaks  disapproval  or 
bewilderment.  The  risorius,  or  grinning  muscle,  draws  the  corners  of  the 
mouth  outward.  The  sneering  muscle  lifts  the  nostril  and  lip  together. 
Pleasure  is  expressed  by  the  lifting  of  the  angles  of  the  lips  upward  and 
outward,  while  grief  depresses  them.  (There  are  but  three  of  the  depress- 
ors, or  grieving  muscles,  on  each  side,  and  six  for  the  manifestation  of  hap- 
pier feelings.) 

MUSCLES  OF  MASTICATION,  FIVE  IN  NUMBER 

The  temporal  muscle. — Occupying  the  entire  temporal  fossa. 
Origin. — The  floor  of  the  fossa,  and  the  temporal  fascia  covering 
it.  Insertion. — The  coronoid  process  of  the  mandible. 

Action. — It  closes  the  mouth  and  draws  the  mandible  or  lower 
jaw-bone  backward. 

N '  erve.-^-Fifth  cranial  (or  tri-facial). 

The  masseter.— At  the  side  of  the  face  (Fig.  78).  Origin.— 
The  zygomatic  arch.  Insertion. — The  lateral  surface  of  the  ramus 
of  the  mandible. 

Action. — It  closes  the  mouth  and  moves  the  jaw  forward 
slightly. 

Nerve. — Fifth  cranial. 


RIBBON   MUSCLES  91 

The  internal  pterygoid. — In  the  infra-temporal  fossa  covered  by  the 
ramus  of  the  mandible  on  which  it  is  inserted. 

Action. — It  closes  the  mouth  and  moves  the  jaw  forward  and  sideways. 

External  pterygoid. — Also  in  the  infra-temporal  fossa  and  inserted  on  the 
mandible. 

Action. — It  moves  the  jaw  forward  and  sideways. 

Nerve. — Fifth  cranial. 

Buccinator. — Origin,  from  both  the  maxilla  and  the  mandible  on  the 
alveolar  borders.  The  fibers  approach  each  other,  interlacing  and  running  for- 
ward; some  of  them  join  the  lip  muscles,  constituting  the  insertion  (Fig.  78). 

Action. — It  helps  to  close  the  mouth,  and  keeps  the  food  between  the  teeth 
during  the  act  of  mastication. 

Nerves. — Fifth  and  seventh  cranial. 


Temporal 


Buccinator 


FIG.  77. — THE  TEMPORAL  MUSCLE. — (Morris.) 


By  the  action  of  the  first  four  muscles  the  food  is  divided  and 
crushed,  and  also  ground;  the  external  pterygoid  is  especially  a 
grinding  muscle.  The  function  or  use  of  these  four  would  be 
somewhat  limited  without  the  aid  of  the  buccinator. 

MUSCLES  IN  THE  FRONT  OF  THE  NECK 

The  ribbon  muscles,  thin  and  flat,  connecting  the  larynx  and 
hyoid  bone  above,  with  the  sternum,  rib,  and  clavicula  below. 


9 2  ANATOMY   AND   PHYSIOLOGY 

They  are  the  sterno-hyoid,  the  sterno- thyroid,  and  the  omo-hyoid  (a 

double-bellied  muscle  with  an  intervening  tendon,  the  inferior  belly  being 
attached  to  the  upper  border  of  the  scapula,  the  superior  belly  to  the  hyoid 
bone,  while  the  tendon  between  them  glides  through  a  loop  of  fascia  attached 
to  the  clavicula). 


FIG.  78. — MUSCLES  IN  FRONT  or  THE  NECK. 

"i,  2,  3,  Digastric  muscle;  4,  stylo-hyoid;  5,  mylo-hyoid;  6,  hyo-glossus;  7,  8,  9, 
sterno-mastoid;  10,  n,  12,  13,  14,  ribbon  muscles;  15,  pharynx;  16,  occipitalis;  17, 
ear  muscles;  18,  trapezius;  19,  20,  splenius;  21,  levator  scapulae;  22,  23,  scalene;  24, 
deltoid;  25,  pectoralis  major;  26,  right  platysma;  27,  28,  lip  muscles;  29,  masseter; 
30,  buccinator. — (Sappey.} 

Action  of  the  three  muscles. — They  draw  the  hyoid  bone  and 
the  larynx  downward,  and  steady  them. 

Nerves. — Ninth  cranial,,  or  hypoglossal. 

The  digastric  is  another  double-bellied  muscle  (Fig.  78). 

The  posterior  belly  is  attached  to  the  mastoid  process  (medial  surface) ; 
the  anterior  belly  to  the  under  surface  of  the  mandible  close  to  the  symphysis. 
The  intervening  tendon  glides  through  a  loop  of  fascia  connected  with  the 
hyoid  bone. 

Action. — It  draws  the  mandible  downward,  and  opens  the 
mouth.  (It  is  assisted  by  some  other  short  muscles  connecting  the 
mandible  to  the  hyoid  bone.) 

Nerves. — Fifth  and  seventh  cranial. 


STERNO-CLEIDO-MASTOID  93 

The  mylo-hyoid  (Fig.  78)  is  a  flat  muscle  which  forms  the  floor 
of  the  mouth,  being  attached  by  one  border  to  the  inner  surface  of 
the  body  of  the  mandible,  and  by  the  other  to  the  hyoid  bone, 
which,  it  will  be  remembered,  is  on  a  level  with  the  mandible. 

Action. — It  can  draw  the  hyoid  bone  forward  in  the  act  of 
swallowing,  thus  keeping  the  larynx  out  of  the  way  of  the  food. 

Nerve. — Fifth  cranial. 

The  platysma. — As  the  muscles  of  the  back  and  side  of  the  neck  are  covered 
by  the  trapezius,  so  those  of  the  front  and  side  are  covered  by  the  platysma, 
which  is  a  broad  thin  sheet  of  muscular  fibers  attached  above  to  the  mandible 
and  the  fascia  of  the  side  of  the  face,  and  below  to  the  deep  fascia  on  the  front 
of  the  shoulder  (Fig.  76).  Like  the  face  muscles,  it  is  not  covered  by  deep 
fascia,  and,  since  it  moves  the  skin,  it  is  like  them  a  muscle  of  expression.  It 
draws  the  angle  of  the  mouth  downward,  and  strong  contractions  of  the 
muscle  assist  in  causing  an  appearance  as  of  one  in  a  "great  rage."  The 
action  of  this  muscle  in  grazing  animals  is  displayed  when  used  to  shake  off 
insects  which  alight  upon  the  skin  of  the  neck. 

Nerve. — Seventh  cranial. 

The  sterno-cleido-mastoid  (Figs.  78).  is  the  most  conspic- 
uous muscle  in  the  side  of  the  neck.  Origin. — By  two  divi- 
sions, one  on  the  sternum  (sternal,  or  medial  origin),  the  other  on 
the  clavicula  (clavicular,  or  lateral  origin).  Insertion. — The 
mastoid  process  and  upper  curved  line  of  the  occipital  bone. 

Action. — Principally  to  pull  the  mastoid  process  toward  the 
sternum  and  clavicula.  If  the  right  muscle  contracts  the  right 
mastoid  process  comes  downward  and  forward  and  the  chin  turns 
upward  to  the  left.  If  the  left  muscle  contracts  the  left  mastoid  is 
pulled  downward  and  forward  and  the  chin  goes  upward  to  the 
right.  Both  muscles  together  simply  bend  the  head  forward,  or 
flex  it. 

Nerves. — Spinal  accessory  (and  cervical). 

Clinical  note. — The  sterno-mastoid  is  another  muscle  which  is  sometimes 
the  seat  of  spasmodic  contractions,  causing  wry-neck,  or  torticollis. 

Levator  scapulae. — The  elevator  of  the  scapula  is  an  important  muscle 
in  the  side  of  the  neck.  Origin. — The  upper  three  or  four  transverse  processes. 
Insertion. — The  medial  angle  of  the  scapula. 

Nerves. — Cervical. 


94 


ANATOMY   AND   PHYSIOLOGY 


THE  ABDOMINAL  WALL 

The  abdominal  wall  has  no  bones  except  the  lumbar  vertebrae, 
being  mostly  muscular  and  aponeurotic.  Each  lateral  half  is 
composed  of  one  vertical  muscle  in  front,  next  to  the  median  line; 
another  in  the  back,  next  to  the  spinal  column;  and. three  well- 
developed  layers  having  fibers  of  different  directions,  at  the  sides. 

Rectus  abdominis  (Fig.  80). — This  is  the  vertical  muscle  in 
front.  Origin. — The  body  of  the  pubes.  Insertion. — The  ensi- 


±3 

FIG.  79. — ANTERIOR  SURFACE  OF  THE  ABDOMINAL  WALL. 
*»  2>  3»  7 1  Pectoralis  major;  4,  external  oblique;  5,  serratus  anterior;  6,  latissimus 
dorsi;  8,  xiphoid  appendix;  9,  9,  15,  aponeurosis  of  ext.  oblique;  10,  14,  linea  alba;  n, 
umbilicus;  12,  transverse  lines  of  aponeurosis;  13,  13,  subcutaneous  abdominal  ring; 
16,  17,  18,  19,  refer  to  muscles  of  neck;  20,  deltoid. — (Sappey.)  Lower  border  of 
aponeurosis  is  inguinal  ligament. 

form  appendix  and  the  cartilages  of  the  fifth,  sixth,  and  seventh 
ribs.     It  is  therefore  narrow  below  and  broad  above,  and  its  outer 


ABDOMINAL  MUSCLES  95 

border  is  curved  from  the  seventh  rib  down  to  the  pubes.  This  is 
indicated  in  the  fascia  over  the  muscle  by  a  distinct  line  called 
the  semilunar  line  (linea  semilunaris). 

Action. — It  compresses  the  abdominal  organs. 

Nerves. — Lower  thoracic  and  first  lumbar. 

Quadratus  lumborum. — This  is  the  vertical' ^muscle  at  the 
back  (Fig.  74).  Origin. — The  crest  of  the  ilium.  Insertion.— 
The  lowest  rib  and  transverse  processes  of  the  upper  lumbar 
vertebrae.  It  occupies  the  space  at  the  back  of  the  trunk  between 
the  thorax  and  pelvis,  being  covered  by  the  erector  spinae  and 
latissimus  dorsi  muscles. 


m 

FIG.  80. — INTERNAL  OBLIQUE  AND  TRANSVERSE  MUSCLES. 
i,  Rectus  abdominis;  2,  2,  3,  3,  internal  oblique  and  cut  edge  of  its  aponeurosis; 
4,  4,  cut  edge  external  oblique;  5,  5,  spermatic  cords;  6,  aponeurosis  ext.  oblique 
turned  down;  7,  rectus,  upper  part  removed;  8,  8,  9,  transversus  muscle;  10,  umbilicus; 
n,  12,  linea  alba;  13,  serratus  anterior;  14,  15,  cut  edge  latissimus  dorsi;  17,  17, 
external  intercostal;  19,  cut  edge  external  oblique. — (Sappey.) 

Action. — It  draws  the  rib  down  and  the  spine  to  one  side— 
lateral  flexion  of  the  trunk . 

Nerves. — Lower  Thoracic. 

The  three  layers  at  the  side  and  front  consist  of  the  obliquus 
externus  or  external  oblique;  the  obliquus  internus,  or  internal 


96  ANATOMY   AND    PHYSIOLOGY 

oblique;  and  the  transversus  muscles.  They  occupy  the  space 
between  the  eight  lower  ribs  above,  and  the  ilium  and  pubes 
below.  Being  broad  and  flat  they  do  not  possess  tendons  of  the 
usual  kind,  but  many  of  their  muscle  fibers  terminate  in  layers  of 
white  fibrous  tissue  called  aponeuroses,  which  continue  to  the 
median  line,  there  blending  with  the  layers  from  the  opposite  side. 
This  produces  a  firm  interlacing  of  white  fibers  called  the  linea 
alba  or  white  line,  stretched  between  the  ensiform  appendix  above 
and  the  body  of  the  pubes  below.  It  is  a  very  strong  and  impor- 
tant line,  through  which,  a  little  below  the  middle,  the  umbilical 
cord  passes  in  the  fetus;  this  point  in  the  linea  alba  is  indicated 
by  the  umbilicus,  or  navel. 

The  external  oblique  (Fig.  79)  is  the  outermost  of  the  three 
layers.  Origin. — The  lower  eight  ribs.  Direction  of  fibers, 
downward  and  forward.  Insertion. — Some  fibers  on  the  crest 
of  the  ilium;  others  in  an  aponeurosis  which  passes  to  the  linea 
alba. 

Nerves. — Lower  thoracic. 

Special  point. — The  lower  border  of  the  aponeurosis  of  this  muscle  between 
the  spine  of  the  ilium  and  the  spine  of  the  pubes  is  firm  and  unyielding,  easily 
felt,  and  important  to  be  recognized;  it  is  called  the  inguinal  ligament  (or 
Poupart's  ligament). 

The  internal  oblique  (Fig.  80)  lies  underneath  the  external 
oblique.  Origin. — The  lumbar  fascia,  crest  of  the  ilium,  and 
lateral  half  of  the  inguinal  ligament.  Direction  of  fibers,  upward 
and  forward.  Insertion. — Some  fibers  on  the  lower  three  ribs, 
others  in  the  linea  alba,  and  the  lowest  ones  on  the  crest  of  the 
pubes. 

Nerves. — Lower  thoracic  and  first  lumbar. 

The  transversus  (Fig.  80)  is  the  innermost  of  the  three  layers. 
Origin. — The  lower  six  ribs,  the  lumbar  fascia,  crest  of  the  ilium, 
and  lateral  half  of  the  inguinal  ligament.  Direction  of  fibers, 
transversely  across  the  side  of  the  abdomen,  toward  the  front. 
Insertion. — In  the  linea  alba,  and  the  crest  of  the  pubes.  On 
the  pubes  it  is  blended  with  that  part  of  the  internal  oblique  which 
is  attached  to  the  same  bone,  making  the  conjoined  tendon. 

Nerves. — Lower  thoracic  and  first  lumbar. 

Action,  of  the  three  broad  muscles. — They   compress   the 


SHEATH  OF  RECTUS  MUSCLE 


97 


abdominal  viscera  and  expel  the  contents  of  those  which  are 
hollow. 

The  fibers  from  the  inguinal  ligament,  of  both  internal  oblique  and  trans- 
versus  muscles,  arch  downward  to  the  pubes. 

SHEATH  OF  THE  RECTUS  ABDOMINIS  (FIGS.  79,  80) 

In  the  lower  fourth  of  the  linea  semilunaris,  the  entire  thick- 
ness is  continued  forward  as  one  layer  in  front  of  the  muscles. 
In  the  upper  three-fourths  the  linea  semilunaris  divides  into  two 
layers  which  meet  again  in  the  linea  alba;  thus  a  compartment  is 
formed  to  be  occupied  by  the  rectus  muscle. 

This  is  called  the  sheath  of  the  rectus,  with  its  anterior  and 
posterior  layers,  the  anterior  layer  being  thickest  and  strongest  in 
the  lower  part  where  the  greatest  strain  would  be  brought  upon  it. 

Linese  transversae  (transverse  lines). — At  three  different  levels 
above  the  umbilicus  the  anterior  layer  of  the  sheath  is  held  down 
to  the  rectus  muscle  by  fibers  forming  transverse  lines. 

Note. — The  location  of  all  these  markings — the  semilunar  line,  the  white 
line,  and  the  three  transverse — may  be  seen  on  the  surface  of  the  body  during 
the  action  of  the  muscles;  and  in  a  piece  of  statuary  representing  the  trunk 
they  should  be  plainly  indicated  (Fig.  79). 


FIG.  81. — THE  DIAPHRAGM. 
Dotted  lines  indicate  descent  in  contraction. — (Holden  ) 

ROOF  OF  THE  ABDOMEN 

The  roof  of  the  abdomen  is  the  diaphragm;  it  has  no  floor  of 
its  own,  the  pelvic  floor  serving  for  both  cavities  (page  no). 
The  diaphragm. — This  is  a  broad,  thin,  dome-shaped  muscle 
7 


98  ANATOMY   AND    PHYSIOLOGY 

separating  the  abdominal  and  thoracic  cavities.  The  central 
portion  is  aponeurotic,  serving  for  the  insertion  of  the  remaining 
or  muscular  portion. 

Origin. — i.  By  two  vertical  bundles  at  the  sides  of  the  lumbar 
vertebrae.  These  vertical  portions  are  the  crura  of  the  diaphragm. 
Their  fibers  turn  forward,  crossing  and  interlacing  before  they  end 
in  the  central  tendon.  2.  From  arches  of  lumbar  fascia  and  the 
lower  boundary  of  the  thorax  (seventh  to  twelfth  ribs  and  xiphoid 
appendix) . 

Insertion. — In  a  flat  central  tendon,  shaped  like  a  clover  leaf, 
near  the  center  of  the  dome.  The  lateral  portion  of  the  muscle  arch 
is  higher  than  the  central,  forming  a  cupola  on  each  side. 


FIG.  82. — THE  DIAPHRAGM,  INFERIOR  SURFACE. 

e  i,  2,  3,  Tendinous  leaflets;  4,  muscle  fibers;  5,  6,  7,  tendinous  arches;  8,  10,  fibers 
arising  from  vertebrae;  n,  aorta — a  large  artery;  12,  esophagus,  leading  to  stomach; 
13,  opening  for  vena  cava. — (Potter's  Compe'nd  of  Anatomy.} 

Action. — When  the  diaphragm  contracts  it  becomes  flattened, 
pressing  upon  the  abdominal  organs;  when  it  relaxes,  it  springs 
back  to  its  dome-shape,  as  high  as  the  fourth  or  fifth  rib,  pushing 
gently  against  the  lungs.  (See  p.  121.) 

Nerve. — Phrenic  and  lower  intercostal. 

Special  points. — This  muscle ^forms  the  floor  of  the  thorax,  and 
at  the  same  time  the  roof  of  the  abdomen  (convex  floor,  concave 
roof).  There  are  three  openings  in  it  at  the  back  part  for  the 


ILIO-PSOAS 


99 


passage  of  a  large  artery  and  vein — the  aorta  and  vena  cava,  and 
the  esophagus. 

With  the  muscles  thus  far  described  the  walls  of  the  cavities  of 
the  trunk — dorsal  and  ventral — are  completed  (see  page  52). 

INTERIOR  ABDOMINAL  MUSCLES 

The  psoas  major  and  iliacus. — These  are  two  muscles  within 
the  abdomen  (on  the  posterior  wall)  which  pass  out  over  the 
brim  of  the  pelvis  into  the  thigh. 

Psoas  major.  Origin. — The  sides  of  the  lumbar  vertebra?. 
Insertion. — Trochanter  minor  of  the  femur. 


12 


FIG.  83. — ABDOMINAL  MUSCLES,  INTERIOR. 

i-5,"Psoas 'minor  and  major;  6,  attachment  of  psoas  major  to  trochanter  minor, 
7,  7,  8,  8,  iliacus;  9,  9,  cut  tendon  rectus  femoris;  10,  10,  obturator  externus;  11-13 
quadratus  lumborum;  14,  14,  transversus. — (Sappey.) 

Iliacus.  Origin. — The  iliac  fossa.  Insertion. — With  the  psoas 
on  the  trochanter  minor  of  the  femur. 

Action. — They  act  together  as  one  muscle,  the  ilio-psoas,  to 
flex  the  thigh,  at  the  same  time  rotating  it,  so  that  the  foot  turns 
outward. 


100  ANATOMY  AND   PHYSIOLOGY 

Nerves. — Lumbar  and  femoral. 

Surgical  note. — Disease  of  the  lumbar  vertebrae  resulting  in  pus  causes 
psoas  abscess.  The  pus  often  follows  the  muscle  fibers  downward  and  appears 
below  the  inguinal  ligament. 

(The  psoas  minor  is  a  small  muscle  in  front  of  the  major.) 
The  transversalis  fascia  is  a  layer  of  loose  connective  tissue 
which  completely  lines  the  muscles  of  the  abdomen;  it  is  continuous 
with  the  iliac  fascia  on  the  iliacus  muscle  and  with  the  pelvic 
fascia  below. 


CHAPTER  VII 
MUSCLES  OF  THE  EXTREMITIES 

The  muscles  of  the  extremities  are  frequently  named  for  their 
use,  and  they  may  all  be  grouped  according  to  their  action;  as 
flexors,  to  bend  the  joints  over  which  they  pass,  and  extensors  to 
straighten  them;  pronators  and  supinators;  abductors  and  adduc- 
tors; and  rotators,  inward  or  outward.  Their  origins  are  not  only 
from  bones,  but  from  fascia,  and  the  fibrous  septa  between  them. 
This  is  true  of  most  muscles  to  .some  extent,  but  particularly  so 
in  the  extremities. 

The  principal  bony  attachments  only  are  given  here. 

MUSCLES  OF  THE  UPPER  EXTREMITY 

SHOULDER  MUSCLES 

Supraspinatus. — On  thedorsal  surface  ofthe_scapula.  Origin. 
— The  supraspinous  fossa,  the  tendon  passing  over  the  head  of  the 
humerus  to  the  insertion  on  the  top  of  the  greater  tubercle. 

Action. — It  lifts  the  arm  away  from  body  (abduction) . 

Infraspinatus. — Also  on  the  dorsal  surface  of  the  scapula. 
Origin. — The   infraspinous   fossa.  """Insertion. — The   greater    tu~ 
bercle  of  the  humerus  (below  the  supraspinatus) . 

Action. — It  rotates  humerus  outwa.r^l  (the  palm  turns  forward) . 

Nerve,  both  muscles. — Suprascapular. 

Teres  minor.     Origin. — The  axillary  border  of  the^scapula.    Insertion. — 

The  greater  tubercle,  just  below  the  infraspinatus. 

Action. — It  rotates  humerus  outward  (palm  turns  forward}. 

Nerve. — A  xillary. 

Teres  major.  Origin. — Near  the  inferior  angle  of  the  scapula  (on 
axillary  border. )  insertion. — The  shaft  of  the  humerus  (crest  of  lesser Tuber- 
cle),  joining  the  tendon  of  the  latissimus  dorsi  and  acting  with4t  (Fig.  84). 

Action. — It  draws  the  arm  backward,  and  rotates  it  inward  (the  palm 
turns  backward}".  ' -" 

Nerve. — Subscapular  (lower] . 

101 


102 


ANATOMY   AND   PHYSIOLOGY 


Subscapularis    (Fig.    86).     Origin.— The    subscapular   fossa. 
Insertion. — The  lesser  tubercle  of  the  humerus. 

Action. — It  holds  the  head  of  the  humerus  in  place  and  rotates 
it  inward  (the  palm  turns  backward) . 

The  deltoid  (Fig.  85). — Is  triangular  in  shape  and  forms  a 
sort   of   cap   over   the   shoulder- joint.     Origin. — The_  spine   and' 

acromion  of  the  scapula,  and 
the  lateral  portion  ol  the 
clavicula.  Insertion. — The 
jateral  surface  of  the  humerus 
at  the  middle  of  the  shaft, 


"on  the  deltoid  tuberosity. 

Action.-  —  Principally  to 
elevate  the  humerus  to  a 
Horizontal  position  (acting 
with  the  supraspinatus,  an 
abductor  of  the  arm). 


Nerve.  —  A  xillary. 


The 


anterior 


(Figs.  75,  85).—  A  large  flat 


and  important  muscle  wicn 
lies  between  the  scula'lin5 


19. 


FIG.  84. — MUSCLES  OF  THE  SHOULDER 


16%    the  thorax^  Origin.-— By 

17    separate  slips  from  eight  ribs,  _ 

on  the  front  and  side  of  the 
Thorax,    insertion. — The  ver- 
tebral Sdrder  of  the  scamrfa^ 
It  lies  close   to  the  side  of 
the   thorax,  covering  a  con- 


2,  3,  4,  5,  Triceps;  6,  attachment  to    siderable  portion  of  the  ribs  t 


olecranon;  7,  anconeus;~8,  8,  g,jieltoid  (por- 
tion removed);  10,  supraspinatus;  n,  infra- 
spinatus;  12,  13,  two  extremities  of  teres 
minor  (intervening  portion  removed);  14, 


and  intercostal  muscles. 
Three  actions. — It  holds 


teres  major;  15,  latissimus  dorsi;  16,  17,  18,     the    scapula   firmly    in    plafo 
19,  muslces  of  forearm.-T^^.)  and    pulls    it    forward^  thus 

pushing  the  arm   ahead.     If  the  shoulders  are  held  firmly  jt  can_ 

elevate  the  ribs,  assisting  inspiration.     It  sustains  the  weight  of 

the  body  when  resting  upon  hands  and  knees,  as  in  creeps 

Nerve. — Long  thoracic  or  external  respiratory. 


PECTORAL   MUSCLES 


103 


BREAST  MUSCLES 

Pectoralis  major.  Origin. — Clavicular  portion,  on  the  sternal 
end  of  the  calvicula;  sterno-costal  portion,  on  the  surface  of  the 
sternum  and  on  six  upper  ribs.  Insertion. — By  a  broad  strong 
tendon  on  the  shaft  of  the  humerus,  on  the  crest  of  the  greater 
tubercle  (Figs.  79,  85). 

18        19      1R 


10  11 


FIG.  85. — MUSCLES  OF  ANTERIOR  ASPECT  OF  THORAX. 

1-5,  Pectoralis  major;  6,  9,  pectoralis  minor;  7,  subclavius;  8,  deltoid;  10,  anterior 
portion  of  anterior  serratus;  u,  external  oblique;  12,  13,  latissimus  dorsi;  14,  teres 
major. — (Sappey.) 

Action.— It  draws  the  arm  to  the  front  of  the  thorax,  opposing 
the  latissimus  dorsi;  thus  it  also  is  a  " rowing"  muscle. 


Thepectoralis  minor  is  -entirely  covered  by  the  major. 

Origin. — From  three  upper  riba^the  second,  third,  and  fourth.  In- 
sertion.— Th^coracoid  process  of  the  scapula.  Action. — It  pulls  the  shoulder 
downward.  It  may  pull  ribs  upward  in  labored  breathing  or  forced  inspira- 


Nerves  of  both  muscles. — Anterior  thoracic. 

Note. — When  the  whole  body  is  drawn  upward  by  the  hands, 
as  when  hanging  from  a  trapeze,  the  two  pectorals,  the  trapezius 
and  the  latissimus  are  acting  together. 

The  subclavius  is  a  small  muscle  lying  in  the  subclavian  groove  between 
the  clavicula  and  first  rib.  It  may  elevate  the  ribs  or  depress  the  clavicula. 


IO4 


ANATOMY   AND    PHYSIOLOGY 


ARM  MUSCLES 
Anterior 

Biceps  brachii  (a  two-headed  muscle).     Origin. — The  scapula: 
the  long  head  above  the  glenoid  fossa,  and  the  short  head  on  the  cora- 

coid  process.  Insertion. — By  one 
tendon  on  the  tuberosity  of  the 
radius  (Fig.  86). 

Nerve. — Musculo-cutaneous. 


7-1: 


FIG.  86. — MUSCLES  OF  THE  ARM. 
2,  3,  5,  Biceps  and  bicipital  fas- 


cia; 4,  attachment  of  biceps  to  tuber- 
osity of  radius;    6,   coracobrachialis;    radial. 
7,   8,^  insertion   of   pectoralis   major; 
9,  latissimus cisis! (insertion);  10,  teres 
major;    n,    subscapularis;     12,    bra- 
chialis;   13,   14,  two  heads  of  tricepsr 
— (Sappcy.) 


Note. — If  the  biceps  brachii  begins 
to  contract  while  the  hand  is  pronated, 
the  first  effect  would  be  to  pull  the 
radial  tuberosity  around  and  place  the 
hand  in  the  supinated  position,  then 
flexion  would  follow;  in  other  words, 
the  biceps  may  act  as  both  a  supinator 
and  flexor. 

The  coraco-brachiaKs. — A  smaller 
muscle,  close  to  the  biceps.  Origin. — 
The  tip  of^  the  coracoid  process.  In- 
sertion.^nJe  shaft  of  hum  ems,  medial 
side,  opposite  the  deltoid. 

Action. — It  lifts  the  humerus  forward^ 

Nerve. — Muscuio-vutaneous. 

The  brachialis. — Is  underneath  the 
biceps.  Origin. — The  anterior  surface 
of  the  humerus.  Insertion. — The  tu- 
bercle of  the  ulna,  just  below  the  coro- 
noid  process. 

Action. — With  the  biceps  it  flexes 
the  forearm. 

Note. — This  is  a  broad  muscle  and 
covers  the  front  of  the  elbow-joint. 

Nerve.  —  Musculo  -  cutaneous    and 


ARM   MUSCLES 
Posterior  FIG.  84 

The  trjflnpri  hrnrhii  „  (-}  three- 
headed  muscle).  Origin. — The  long  head,  on  the  scapula,  just 
below  the  glenoid  fossa;  the  medial  and  lateral  heads  on  the  pos- 
terior surface  of  the  humerus,  separated  by  the  groove  for 


FLEXORS   OF   FINGERS  105 

dial  nerve.    Insertion. — The  (top  of  the)  olecranpn  process  of  the 
ulna. 

Action. — It  extends  the  forearm  (opposing  the  biceps). 

Nerve. — Radial. 

Note. — The  back  of  the  triceps  is  covered  at  its  lower  portion  by  a  fibrous 
layer  (aponeurosis)  which  receives  many  of  the  muscular  fibers.  In  action, 
the  three  heads  swell  while  this  fibrous  layer  remains  flat. 

MUSCLES  OF  THE  FOREARM 
Anterior 

The  superficial  flexors. — The  medial  epicondyle  of  the  humerus 
gives  origin  to  a  group  of  superficial  muscles  which  flex  the  wrist, 
and  fingers  (Fig.  87). 

Flexor  carpi  radialis,  or  radial  flexor  of  the  wrist.  Origin.— 
The  medial  epicondyle.  Insertion. — The  base  of  the  second 
metacarpal  bone  (that  of  the  index-finger). 

Nerve. — Median. 

Flexor  carpi  ulnaris,  or  ulnar  flexor  of  the  wrist.  Origin.— 
The  medial  epicondyle  and  dorsal  border  of  the  ulna.  Insertion.— 
The  base  of  the  fifth  metacarpal  bone  (after  attachment  to  the 
pisiform  and  unciform  bones). 

Action  of  the  two. — To  flex  the  wrist. 

Nerve. — Ulnar. 

Flexor  digitorum  sublimis,  or  superficial  flexor  of  the  fingers. 
Origin. — The  medial  epicondyle,  the  upper  extremity  of  the  ulna, 
and  the  shaft  of  the  radius  (the  three  long  bones) .  Insertion. — By 
four  tendons,  one  for  each  finger,  on  the  second  row  of  phalanges. 

Action. — It  flexes  the  second  joints,  of  the  fingers,  but  not  the 
finger-tips. 

Nerve. — Median. 

Deep  flexors. — The  shafts  of  the  bones  give  origin  to  the  deep 
flexors  of  the  fingers  and  thumb,  which  act  upon  the  third  row  of 
phalanges. 

Flexor  digitorum  profundus,  or  deep  flexor  of  the  fingers. — Is  underneath 
the  superficial  flexor.  Origin. — The  shaft  of  the  ulna.  Insertion. — By  four 
tendons,  on  the  third  or  last  row  of  phalanges. 

Action. — It  flexes  the  finger-tips. 


io6 


ANATOMY  AND   PHYSIOLOGY 


FIG.  87. — MUSCLES  OF  THE  FOREARM. 
i,  2,  4,  4,  5,  Muscles  of  arm;  3,  tendon 
of  insertion  of  biceps;  6,  round  pronator; 
7,  radial  flexor  of  wrist;  8,  9,  palmaris 
longus;  10,  n,  ulnar  flexor  of  wrist;  12, 13, 
brachio-radialis;  14-18,  muscles  and  ten- 
dons belonging  td  posterior  of  forearm; 
19,  19,  superficial  flexor  of  fingers;  20,  20, 
21,  21,  tendons  of  the  same,  showing 
fissure;  22,  22,  tendons  of  deep  flexor  com- 
ing through  fissure  to  reach  the  third  row 
of  phalanges. — (Sappey.) 


FIG.  88. — MUSCLES  OF  THE  FOREARM, 

DORSAL  ASPECT. 

i,  Aponeurosis  of  triceps;  2,  upper 
end  of  brachio-radialis;  3,  4,  long  radial 
extensor  of  wiist;  5,  6,  short  radial  ex- 
tensor of  wrist;  7,  8,  8,  9,  9,  extensors  of 
thumb;  10, 10,  annular  ligaments;  n,  12, 
12,  common  extensors  of  fingers;  13,  14, 
special  extensors  for  index  and  little 
fingers:  15,  16,  ulnar  extensor  of  wrist; 
18,  ulnar  flexor  of  wrist;  19,  posterior 
border  of  ulna;  20,  olecranon  process  of 
ulna;  21,  media  lepicondyle. — (Sappey.) 


PRONATORS  107 

Note. — Since  the  tendons  of  the  superficial  flexor  stop  at  the  second 
phalanges,  while  those  of  the  deep  flexor  pass  to  the  third  phalanges,  there  is  a 
fissure  in  each  superficial  tendon  just  before  it  ends,  through  which  the  deep 
tendon  passes  forward  to  the  bone  of  the  finger-tip  (Fig.  87). 

Nerves. — Median  and  ulnar. 

Flexor  pollicis  longus,  or  long  flexor  of  the  thumb. — Origin. — The  shaft  of  the 
radius  (under  flexor  sublimis).  Insertion. — The  last  phalanx  of  the  thumb. 

Action. — It  flexes  the  tip  of  the  thumb. 

Nerve. — Median. 

Note. — These  tendons  for  the  fingers  and  thumb  lie  in  the 
deep  groove  on  the  front  of  the  carpus.  Friction  between  them  is 
prevented  by  sheaths  of  synovial  membrane — vaginal  synovial 
membranes. 

THE  Two  PRONATORS,  THE  ROUND  AND  THE  SQUARE 

Pronator  teres,  or  round  pronator  (Fig.  87). 

Origin. — The  medial  epicondyle,  and  a  small  slip  from  the 
ulna  (coronoid  process).  It  passes  across  to  the  lateral  side  of  the 
radius,  to  the  insertion  at  the  middle  of  the  shaft. 

Nerve. — Median. 

Pronator  quadratus,  or  square  pronator. 

Origin. — The  shaft  of  the  ulna.  Insertion. — The  shaft  of  the  radius.  It 
lies  just  above  the  wrist  and  underneath  the  long  muscles  (close  to  the  bones). 

Nerve. — Median. 

Action  of  the  two  pronators. — They  rotate  the  radius  so  as  to 
turn  the  palm  downward  (or  backward). 

One  slender  muscle,  which  is  superficial  to  all,  is  the  palmaris  longus. 
It  arises  on  the  medial  epicondyle  and  is  attached  below  to  the  palmar  fascia 
to  keep  it  tense — a  tensor  of  the  palmar  fascia. 

Nerve. — Median. 

Note. — It  is  understood  that  the  muscles  arising  from  the  epicondyle 
have  a  common  tendon  of  origin. 

Practical  point— Observe,  by  experimenting,  that  flexion  and  moderate 
pronation  are  naturally  performed  together,  and  are  associated  in  the  major- 
ity of  the  motions  which  are  required  of  the  upper  extremity. 

MUSCLES  or  THE  FOREARM 
Posterior  (Fie.  88.) 

The  lateral  epicondyle  of  the  humerus  and  the  ridges  above  it 
give  origin  to  the  muscles  which  extend  the  wrist  and  fingers. 


108  ANATOMY   AND   PHYSIOLOGY 

Extensor  carpi  radialis  longus,  or  long  radial  extensor  of  the 
wrist.  Origin. — Lateral  border  and  epicondyle  of  humerus. 
Insertion. — The  base  of  the  second  metacarpal  bone. 

Nerve. — Radial. 

Extensor  carpi  radialis  brevis,  or  short  radial  extensor.  Origin. 
—The  lateral  epicondyle.  Insertion. — The  base  of  the  third 
metacarpal  bone. 

Nerve. — Deep  branch  of  radial. 

Extensor  carpi  ulnaris,  or  ulnar  extensor  of  the  wrist. — Origin. 
-The  lateral  epicondyle  and  dorsal  border  of  the  ulna.    Inser- 
tion.— The  base  of  the  fifth  metacarpal  bone. 
Action  of  the  three. — They  extend  the  wrist. 

Nerve. — Deep  branch  of  radial. 

Extensor  digitorum  communis,  or  common  extensor  of  the 
fingers.  Origin. — The  lateral  epicondyle.  Insertion. — By  four 
tendons,  on  the  second  and  third  rows  of  phalanges,  in  such  a  way 
that  it  can  extend  the  bones  of  either  row  separately  or  both  at  the 
same  time. 

The  little  finger  has  a  special  extensor  for  its  tip  (extensor  minimi  digiti). 
The  index  finger  also  has  a  special  extensor  (extensor  indicis),  and  the  thumb 
has  three — two  for  its  phalanges,  and  one  for  its  metacarpal  bone.  By  forci- 
bly extending  the  thumb  these  three  tendons  are  brought  into  view,  the  one  for 
the  tip  of  the  thumb  being  at  a  little  distance  from  the  other  two;  thus  they 
bound  a  little  hollow  which  has  been  called  the  "anatomic  snuff  box." 

Nerves  of  all. — Deep  branch  of  radial. 

THE  Two  SUPINATORS 

The  supinator.  Origin. — The  lateral  epicondyle  and  upper 
end  of  the  shaft  of  the  ulna.  It  winds  around  the  head  and  neck 
of  the  radius  to  the  insertion  on  upper  part  of  the  shaft.  This  is 
the  chief  supinator;  it  is  entirely  covered  -by  other  muscles. 

Action. — It  rotates  the  radius  and  turns  the  dorsum  of  the 
hand  downward  or  backward. 

Nerve. — Deep  branch  of  radial. 

The  branchio-radialis  (Fig.  87).  Origin. — The  lateral  border 
of  the  humerus.  Insertion. — The  styloid  process  of  the  radius. 


THENAR   AND    HYPOTHENAR   MUSCLES  IOQ 

Action. — It  assists  in  both  flexion  and  supination  of  the  forearm. 
(This  muscle  was  formerly  called  the  long  supinator.) 
Nerve. — Radial. 

Annular  Ligaments 

These  are  special  bands  of  deep  fascia  holding  in  place  those 
tendons  which  pass  the  wrist-joint.  They  include  the  tendons  in 
canals  through  which  they  glide  freely.  Friction  is  prevented  by 
synovial  sheaths  within  the  canals.  The  fascia  which  binds  down 
the  extensor  tendons  is  the  dorsal  ligament  of  the  wrist;  that  which 
confines  the  flexor  tendons  is  the  transverse  ligament  of  the  wrist. 

MUSCLES  OF  THE  PALM  (Fie.  87) 

There  is  a  group  of  palmar  muscles  which  move  the  thumb  in 
various  directions  (flexion,  abduction,  adduction,  and  so  on). 
They  form  the  elevation  called  the  thenar  eminence,  or  the  "ball 
of  the  thumb."  A  similar  group  for  the  little  finger  forms  the 
hypothenar  eminence. 

They  arise  mostly  on  carpal  bones  and  deep  fascia  and  are  inserted  on  first 
phalanges.  In  the  hollow  of  the  hand  between  these  two  eminences  lie  the 
long  tendons,  already  described,  on  their  way  to  the  fingers;  also  some  small 
muscles  between  them  and  beneath  them. 

The  interosseous  muscles  fill  the  interosseous  spaces.  The  action  of  the 
dorsal  group  is  to  spread  the  fingers  apart  (abduction)  while  that  of  the  palmar 
group  is  to  bring  them  together  (adduction). 

Note. — A  line  drawn  from  the  middle  of  the  wrist  to  the  tip  of  the  middle 
finger  is  called  the  median  line  of  the  hand.  To  abduct  the  fingers  and  thumb 
is  to  draw  them  away  from  this  line — in  other  words,  from  the  middle  finger. 
To  adduct  them  is  to  draw  them  toward  the  middle  finger. 

Nerves. — To  the  hypothenar  muscles. — Ulnar.  To  thenar  muscles. — 
Median  and  ulnar.  To  inter ossei. — Ulnar. 

The  muscles  in  the  palm  are  covered  by  particularly  dense, 
deep  fascia  called  the  palmar  fascia,  or  palmar  aponeurosis. 

MUSGLES  OF  THE  LOWER  EXTREMITY 
The  Pelvis— Interior 

False  pelvis. — The  iliacus  is  the  only  muscle  in  the  false  pelvis; 
it  is  already  described  with  the  psoas  major,  page  99. 


no 


ANATOMY   AND   PHYSIOLOGY 


True  pelvis. — The  piriformis  and  obturator  interims.  These 
muscles  arise  from  the  interior  of  the  pelvis  and  pass  out  through 
the  sciatic  notches — the  piriformis  through  the  greater  notch  and 
the  obturator  internus  through  the  lesser  notch.  They  are 
inserted  on  the  great  trochanter  and  act  to  rotate  it  outward. 

They  are  supplied  by  nerves  which  are  branches  of  the  sacral 
plexus. 

They  are  short  muscles  but  thick  and  very  strong. 

The  floor  of  the  pelvis  consists  of  two  flat  muscles  on  either  side, 
the  levator  ani  and  the  coccygeus. 


Sacrum 


piriformis 


Coccyx 1 


Levator  ani  (di- 
vided below 
the  "white 
line") 

Space  for  obtu- 
rator internus 

Rectum 
Prostate 


Symphysis 


Passage  for  glu- 
teal  vessels 
and  nerve 

Piriformis 

Passage  for  sci- 
atic and  pu- 
dic  vessels 
and  nerve 

Ischial  ?pine 

Coccygeus 
Cellular  interval 
Levator  ani 


Capsule  of  pros- 
tate, and  pu- 
bo-  prostatic 
ligaments 


FIG.  89. — INTERIOR  AND  FLOOR  OF  THE  TRUE  PELVIS. — (Morris.} 


The  origin  is  on  the  interior  of  the  pelvic  wall — that  is,  on 
the  pubic  bone  and  the  spine  of  the  ischium,  and  a  line  of  fascia 
between  the  two  points.  Insertion. — The  muscles  meet  each 
other  in  the  median  line,  being  also  attached  to  certain  pelvic 
organs  (bladder  and  rectum  in*  the  male;  bladder,  rectum,'  and 
vagina  in  the  female)  and  to  the  coccyx.  Th'eir  action  supports 
the  pelvic  organs,  espe'cially  the  rectum,  and  lifts  them  in  various 
motions  of  the  body,  as  in  respiration. 

Nerves. — From  sacral  nerves. 

Special  notes. — These  two  muscles  form  a  concave  floor  like  an  inverted 
dome,  which  is  the  pelvic  diaphragm.  When  this  dome  contracts  it  rises. 

There  are  two  openings  in  the  pelvic  floor  for  the  bladder  and  rectum,  and 
a  third  opening  in  the  female  pelvis  for  the  vagina. 


GLUTEUS   MAXIMUS 


III 


The  pelvic  fascia  is  a  continuation  of  the  transversalis  fascia 
which  lines  the  abdomen  and  of  the  iliac  fascia  which  covers  the 
iliacus  muscle.  It  covers  the  obturator  muscle  and  its  fascia  and 
the  muscles  of  the  floor,  and  forms  ligaments  for  the  pelvic  viscera. 

THE  PELVIS — EXTERIOR 

Three  gluteal  muscles. — From  the  three  gluteal  lines  of  the  os 
coxae  and  the  spaces  above  them,  arise  three  gluteal  muscles. 

Gluteus  minimus.  Origin. — The  in- 
ferior line  and  space  above  it.  Insertion. 
—The  front  of  the  great  trochanter. 

Action. — It  abducts  the  thigh  and  ro- 
tates the  femur  slightly  inward  (so  that 
the  foot  turns  in). 

Gluteus  medius.  Origin. — The  an- 
terior or  middle  line  and  space  above  it 
up  to  the  crest.  Insertion. — The  outer 
surface  of  the  great  trochanter. 

Action. — Abduction  of  the  femur  and 
some  rotation  outward. 

Nerve  of  both. — Superior  gluteal. 

Gluteus  maximus.    Origin.— 

The  posterior  line  and  space  behind 
it  to  the  crest  (also  from  the  back 
of  sacrum) .  Insertion. — The  back^ 
of  great  trochanter  and  the  ridge 
below  it,  also  the  deep  fascia,  or 
fascia  lata. 

Action. — External  rotation  of  the 
femur;  it  is  also  a  powerful  exten- 


FIG.  90. — THE  GLUTEUS  MAXTMUS. 
(Fascia  removed.) — (Sappey.} 


sor  of  the  hip-jonr| 
nTm6unting  steps. 


when  one  rises  from  the  sitting  position,  or 
It  also  abducts  the  thigh. 


Nerve. — Inferior  gluteal. 

Obturator  externus.  Origin. — The  obturator  membrane  and  bone  around 
it.  Insertion. — The  fossa  of  the  great  trochanter.  Action. — External  rota- 
tion of  the  femur.  (Fig.  83.) 


Nerve. — Obturator. 


112 


ANATOMY  AND   PHYSIOLOGY 


Practical  point. — Observe  the  number  of  muscles  for  external 
rotation  and  note  that  the  usual  position  of  the  foot  is  with  the 
toes  turned  outward. 


FIG.  91. — MUSCLES  OF  THE 
THIGH. 


MUSCLES  OF  THE  THIGH 
Anterior 

On  the  front  and  the  sides  of  the 
femur  are  the  muscles  which  extend  the 
Jeg^-four  in  number;  they  blend  at  their 
insertion  and  therefore  constitute  a  four- 
headed  muscle,  the  quadriceps  femoris^ 
They  are  the  rectus  jemons,  the  vastus 
later  alis,  vastus  medialis  and  the  vastus 
intermedius. 

Rectus  femoris.  Origin. — The  an^ 
terior  inferior  spine  pf  tV>p  j]jujn  and  the 
upper  border  of  the  acetabulum.  The 
three  vasti.  Origin.' — On  the  linea  as- 
pera  and  the  three  surfaces  of  the  femur. 
Insertion  of  the  four. — By  one  tendon 
passing  in  front  of  the  knee^joml  L6""the 
tubercle  of  me  tibia.  (It  encloses  the 
patella  and  has  been  improperly  called 
the  ligamentum  patellae.) 

Action. — They  extend  the  leg  as  in 
walking,  or  with  great  force  in  kicking; 
these  muscles  also  keep  the  patella  in 
place  during  various  positions  of  the 
knee. 

Nerve. — Femoral. 

The  sartorius. — The  longest  muscle 


i,  2,  Iliacus  aftd  psoas;  3,     .  _ ,- 

4,  tensor  fascia;  lata;:  5,  sar-   in  the  body;  it  passes  across  the  front 


.   the  quadriceps.    Origin.-Thejmte- 

medialis;  9,  gracilis;  10,  ad-    rior  superior  spine  nf  fh«*  ilnirn       Inser- 

i     r  ~"  ,.,. 

. — me  inner  surface  of  the    tibia, 

just  below  the  head. 

Action.- — Since  it  passes  across  to  the  medial  side  of  the  thigh, 
and  behind  the  medial  epicondyle,  it  flexes  the  leg  and  at  the 


HAMSTRING   MUSCLES 


same  time  lifts  it  in  such  a  way  that  when  both  legs  are  acted 
upon  together,  they  are  flexed  and  crossed,  hence  the  name, 
signifying  "tailor"  muscle" 

Nerve. — Femoral. 

The  tensor  fasciae  latae. — Is  attached 
to  the  anterior  part  of  the  crest  of  the 
ilium  between  two  layers  of  the  fascia  lata; 
it  makes  tense  the  lateral  portion  of  the 
fascia  which  is  connected  with  the  tibia, 
or  the  ilio-tibial  band.  (This  is  felt  like 
a  strong  cord  above  the  lateral  epicon- 
dyle.)  It  also  rotates  the  thigh  inward 
(Fig.  91). 

Nerve. — Superior  gluleal. 

MUSCLES  or  THE  THIGH 

Posterior 

The  muscles  are  three  in  num- 
ber— the  biceps  femoris,  semitendi- 
nosus,  and  semimembranosus  (Fig. 

93)- 

The  biceps  femoris.    Origin.— 

head  on  trie  Tuber  of  the  is- 
chium,  short  head  on  the  linea  as- 
pera  (lateral  lip).  Insertion. — The 
head  of  the  fibula. 

The  ^emitendinosus  and  the 
semimembranosus  also  arise  on 
the  tuber  of  the  ischium,  and  are 
inserted  on  the  tibia,  medial  sur- 
face and  back  of  head.  (Their 

names  indicate  their  shape,  one  FIG.  92.— MEDIAL  ASPECT  OF  THE 
i •  j.  •  i  if  •,  i  THIGH  AND  PELVIS. 

being  tendinous  m  half  its  length,  ,_  a>  ^  4_  Iliacus>  psoas_  ol,tura. 
and  the  other  aponeuro tic,  or  mem-  tor,  piriformis;  5,  gluteus  maximus; 
branous"  ")  6'  Sartorius5  7.  gracilis;  8,  semitendin- 

osus;  9,  semimembranosus;  10,  n, 
Action.— These  three  muscles  I2'  tendons  of  sartorius,  gracilis,  and 

semitendmosus;  14,  tendon  of  semi- 
act  together  to  flex  the  knee.  membranosus  —  (Sappey.) 

Nerve  to  the  three. — Sciatic. 

Notes.^ — They  also  assist  the  gluteus  maximus  to  extend  the 
thigh,  as  in  rising  from  a  chair.     The  biceps  tendon  may  be  feK 


114 


ANATOMY   AND   PHYSIOLOGY 


Fascial  insertion  of 
gluteus  maximus 


Biceps 


Vastus  laterali  s 


Plan  tans 


Gastrocnemius 


Soleus 


Peroneus  longus 


S  emi-membranosus 


Semi-tendinosus 


Gracilis 

Tendon  of  semi-membranosus 


Sartorius 


Flexor  digitorum  longus 


Tendo  Achillis 


FIG.  93. — POSTERIOR  OF  THIGH  AND  LEG  AND  HAMSTRING  TENDONS. — (Morris.) 


POPLITEAL    SPACE 


behind  the  lateral  epicondyle;  the  two  others,  behind  the  medial 
epicondyle,  making  the  borders  of  a  deep  space — the  popliteal 
space,  or  ham.  They  are  called  "hamstring"  tendons. 

f  Lateral  side,  biceps  femoris. 


Hamstring  tendons. 


Medial  side 


The  popliteus  is  a  flat  muscle  behind  the  knee- 
joint,  forming  part  of  the  floor  of  the  popliteal  space. 

The  most  important  muscles  in  the  me- 
dial side  of  the  thigh  are  the  four  adductors 
(Fig.  94). 

The  adductor  longus.  Origin. — From  the  su- 
perior ramus  of  the  pubes.  Insertion. — The  mid- 
dle of  the  linea  aspera. 

The  adductor  brevis.  Origin. — Upper  part  of 
the  pubic  arch.  Insertion. — The  linea  aspera  be- 
hind and  above  the  longus. 

The  adductor  minimus.  Origin. — The  lower 
part  of  the  pubic  arch.  Insertion. — The  linea 
aspera,  behind  the  brevis  (upper  part). 

The  adductor  magnus.  Origin. — Pubic  arch 
and  tuber  of  the  ischium.  Insertion. — Linea  as- 
pera (behind  the  others),  and  medial  epicondyle. 

Action  of  the  four.— They  all  adduct  the 
femur  (rotating  it  outward)  and  draw  tfieT 
tnighs  together  as  in  horseback  riding. 

tferve  to  the  four. — Obturator,  and  great  sciatic  to 
a  portion  of  adductor  magnus. 

Note. — The  magnus  makes  a  broad  sheet  of  mus- 
cle between  the  quadriceps  which  extends  the  knee, 
and  the  muscles  on  the  back  which  flex  it.  The 
longest  and  strongest  fibers  of  the  magnus  run  between 
the  tuber  of  the  ischium  and  the  medial  epicondyle. 
They  rotate  the  femur  inward. 


semitendinosus. 
semimembranosus. 
sartorius. 
gracilis. 


FIG.  94. — ADDUCTORS. 
i,  2, 3,  Femur,  ilium, 
pubes;  4,  external  obtu- 
rator muscle;  5,  6,  7,  8, 
9,  10,  adductor  muscles; 
n,  12,  openings  for  ves- 
sels passing  to  back  part 
of  thigh. — (Sappey.) 


MUSCLES  OF  THE  LEG 

Anterior 

These  muscles  flex  the  ankle  and  extend  \]\ 
The  muscles  in  the  front  of  the  leg  are  between  the  tibia  and  the 

1  Note. — These  movements  are  dorsal  flexion. 


n6 


ANATOMY  AND   PHYSIOLOGY 


fibula;  the  medial  surface  of  the  tibia,  having  no  muscles  upon  it, 
is  caned  subcutaneous. 

The  tibialis  anterior.    Origin. — The  shaft  and  head  of  the 
tibia  (lateral  surface)  and  the  interosseous  membrane. 

Insertion.' — The  first  cuneiform  and  first 
metatarsal  bones. 


Nerve. — Deep  peroneal. 

The  peroneus  tertius.  Origin. — The  shaft 
of  the  fibula  (lower  part) .  Insertion. — The 
fifth  metatarsal  bone. 

Action  of  the  two.'— To  flex  the  ankle.  The 
tibialis  acting  alone  lifts  the  medial  border  of 
the  foot;  the  peroneus  lifts  the  lateral  border. 

Nerve. — Deep  peroneal. 

The  extensor  hallucis  longus,  or  lon^eo 
tensor  of  the  great  toe._  Origin. — The  shaft  of 
the  fibula  and  the   mterosseous  membrane. 
Insertion. — The  last  phalanx  of  the  great  toe. 

Action. — To  extend  the  great_toe.  ^ 

Nerve. — Deep  peroneal. 

The  extensor  digitorum  longus,  or  long 
extensor  of  the  toes.  Origin.- — The  shaft  of 
the  fibula  and  interosseous  membrane  (a  few 
fibers  from  head  of  tibia).  Insertion. — By 
four  tendons  on  the  second  and  third  pha- 
langes of  the  four  lateral  toes,  like  the  similar 
extensor  of  the  fingers. 

Action. — To  extend  the  toes. 

Nerve. — Deep  peroneal. 

Note. — These  two  muscles,  since  they  pass 


FIG.  95. — MUSCLES 
OF  THE  LEG,  ANTERIOR. 

i,Rectusfemoris;2, 
tibia;  3,   tibialis  ante- 
rior;  4,    long   extensor 
of  toes;  5,  long  extensor 
of  great  toe;  6,  peroneus 
tertius;  7,  8,  "pieroneus^ 
JoHgUS,  p.  brevis;^cJ7*io, 
ta^Terar    amh~medial 
heads,  _gastrocnemiusi. 
n,    short   extensor   oP 
toes;   12,  annular  liga- 
ment. —  (Sappey.) 


in  front  of  the  ankle-joint,  flex  it. 


On  the  dorsum  of  the  foot  the  extensor  digitorum  brevis  has  four  slender 
tendons  for  the  four  medial  toes. 


Nerve. — Deep  peroneal. 


MUSCLES    OF    THE    LEG 


117 


MUSCLES  OF  THE  LEG 


Posterior 

These  muscles  extend  the  ankle  and  flex  the  toes;  they  all  pass 
behind  the  medial  malleolus.     They  are  covered  by  the  calf  muscles. 

The  tibialis  posterior.    Origin. — Shaft  of  bath  tibia  and  fibula  and  the 
interogseous  membrane.    Insertion. — Navicular  and  first  cuneiform  bones. 

Action.— Extension  of  the  ankle. 

Nerve. — Tibial. 

The  long  flexor  of  the  great  toe,  or  flexor  hallucis  lon- 
gus.— Origin.— ^hajt  ot  hbUla.  'Insertion. — Last  phalanx 
of  the  great  toe  (Fig.  96}. 

Nerve. — Tibial. 

Long  flexor  of  the  toes,  or  flexor  digitorum  longus. 
— Origin. — Shaft  of  fibula.  Insertion. — By  four  tendons 
on  the  last  phalanges  of  the  four  lateral  toes  (Fig.  96). 

Action  of  these  two  muscles. — Flexion  of  the  tips  of 
the  toes. 

^erve. — Tibial. 


FIG.  96.— Mus- 


LEG — LATERAL  SIDE  (Fie.  97) 

Peroneus  brevis.  Origin. — Shaft  of  fibula. 
Insertion.— Base  of  fifth  metatarsal  bone.  The 
tendon  passes  behind  the  lateral  malleolus. 

Peroneus  longus.    Origin. — Shaft  of  fibula. 
Insertion. — In  the  sole  of  the  foot,  first  cuneiform 
and  first  metatarsal  bones.     Tlie  tendon  passes  DLE  LAYER. 
behind  the  lateral  malleolus  and  crosses  in  the  cle^V^T 

sole  to  the  medial  border  of  the  foot.  toes    dividing    into 

A    ,.  f     ,  .    four  tendons;  3,  ten- 

Action  of  these  two  muscles. — They  extend  don  of  long  flexor  of 

the  ankle  and  lift  the  lateral  border  of  the  foot?  f^k^ta/muscles' 

Nene  to  both-Superficial  peroneal.  ""iEiTrslSfS 

sheath  of  tendon  of 
JNote. — As  the    tibialis   anterior  and   pero-  peroneus  longus;  n, 

neus  tertius  flex  the  foot,  so  the  tibialis  pos- 
terior and  peroneus  brevis  extend  it. 

Orthopedic  note. — The  P.  longus  makes  a  chord  for  the 
transverse  arch  of  the  foot,  being  the  most  important  muscle  to 
preserve  that  arch  from  being  flattened. 


n8 


ANATOMY   AND    PHYSIOLOGY 


CALF  MUSCLES  (FIGS.  93,  97) 

Triceps  surse,  and  plantaris. 

The  gastrjgcjififliius.     Origin. — Bv  two  hea^s  iust  above  the 

i       i    "5^'^^r     .  i  r 


condyles  of  the  femur. 


Insertion. — On  the  calcaneus. 

Note. — The  two  heads  form  the 
lower  boundaries  of  the  popliteal 
space. 

The  soleus  is  covered  by  the  gas- 
trocnemius.  ^Origin. — Medial  border 
of  the  tibia  and  lateral  border  of  the 
fibula.  Insertion. — The  os  calcis, 
with  trie  above  muscle. 

Action  of  the  two. — They  join  to 
form  one  muscle,  the  triceps  surae  (or 
triceps  of  the  calf),  which  has  the 
strongest  tendon  in  the  body,  the  tendo 
calcaneus  (tendon  of  Achille^)  by 
which  they  are  attached  to  the  os 
calcis,  and,  therefore,  they  lift  the  he'e^ 
If  the  muscles  of  both  legs  act  at  the 
same  time,  the  whole  body  is  lifted  on 
the  toes. 

Nerve  to  both. — Tibial. 

The  plantaris.  Origin.— With  the  outer 
head  of  the  gastrocnemius.  Insertion. — 
With  the  tendo  calcaneus. 

Note. — The  belly  is  short  and  small;  the 


,9-itie 

FIG.  97. — LATERAL  ASPECT  AND 
CALF  or  LEG. 

i,  2,  3,  4,  Lateral  view,  mus- 
cles passing  in  front  of  ankle;  5, 
6,  peroneus  brevis  and  p.  lon- 
gus  (behind  ankle)  ;*  7,  8,  soleus     tendon  is  the  longest  in  the  body, 
and  gastrocnemius;  9,  hea3~Df 

fibula!  10,  biceps  femoris;  n,          The  calf  muscles  constitute  a  group 

Ach^ms^^armula/li  a.men°     °f  &reat  Power>  as  bY  them  one  lifts 
16,  17,  insertions  of  peroneus    oneself  to  stand  upon  the  toes, 
tertius  and  brevis;  18,  short  ex-  ,_.  .    A         £  1^- 

tensor  of  toes;  19,  plantar  mus-          The  sole  of   the  foot,  or  plantar 
cle;  20,  patella.— (Sappe)?.)         region,    resembles    the   palm    of  the 

hand  in  having  special  groups  of  mus- 
cles for  the  great  and  little  toes,  with  the  long  flexor  tendons 
lying  between  them,  and  a  dense  fascia  covering  them.  This  is 
called  the  plantar  fascia. 

The  nerves  are  medial  and  lateral  plantar. 


PHYSIOLOGY   OF   MUSCLES  IIQ 

Annular  Ligaments 

The  tendons  which  pass  from  the  leg  to  the  foot  are  kept  in 
place  by  special  ligaments,  anterior  and  lateral,  and  surrounded  by 
synovial  sheaths  as  in  the  wrists. 

POINTS. — Eversion  of  the  foot,  or  lifting  the  medial  border,  is  done  by  the 
tibialis  anterior. 

Inversion. — Or  lifting  the  lateral  border,  by  the  peroneus  tertius,  and 
peroneus  longus. 

Adduction. — By  deep  posterior  muscles  of  the  leg. 

Abduction. — By  lateral  muscles  of  the  leg. 

RESUME. 

Observe  certain  similarities  and  differences  in  the  extremities. 
Extension  of  the  elbow  is  accomplished  by  the  three-headed  muscle, 
the  triceps.  Extension  of  the  knee  requires  a  powerful  four-headed 
muscle,  the  quadriceps. 

The  great  toe  is  on  the  medial  border  of  the  foot,  the  thumb  is 
on  the  lateral  border  of  the  hand.  This  is  so  because  the  terms 
medial  and  lateral  are  applied  to  the  pronated  position  of  the  lower 
extremity  and  the  supinated  position  of  the  upper  extremity. 

In  the  upper  extremity  the  joints  are  all  flexed  in  one  direction, 
as  though  the  limb  might  be  rolled  up.  In  the  lower  extremity 
they  flex  and  extend  alternately,  as  though  the  limb  were  folded 
back  and  forth. 

STRUCTURE  AND  PHYSIOLOGY  OF  MUSCLES 

A  complete  muscle  is  a  complicated  structure.     It  consists  of: 

First,  the  essential  muscle  substance  in  the  muscle  cells,  p.  83. 

Second,  connective  tissue  wrappings  and  partitions. 

Third,  tendons  or  aponeuroses,  or  both. 

Fourth,  blood-  and  lymph-vessels  in  great  abundance. 

Fifth,  muscle  nerves. 

The  connective  tissue  supports  all  of  the  other  structures  and 
protects  the  muscle,  preserving  its  shape  and  stability. 

The  tendons  and  aponeuroses  provide  a  means  whereby  the 
attachment  to  other  organs  is  kept  within  a  small  space. 

EXAMPLE:  The  biceps  of  the  arm  contains  many  fibers,  but  the  slender 
tendons  of  this  muscle  occupy  only  small  areas  upon  the  surface  of  the  bones. 
The  aponeurosis  of  that  very  powerful  muscle,  the  quadriceps  femoris,  receives 


120 


ANATOMY   AND   PHYSIOLOGY 


the  insertion  of  the  muscle  fibers,  and  by  this  means  only  a  narrow  surface 
is  required  for  insertion  upon  the  bone.  But  for  arrangements  like  these, 
the  skeleton  would  of  necessity  be  inconveniently  large. 

The  blood-vessels  bring  the  nutritive  fluid  which,  in  the  tissue- 
spaces,  bathes  each  little  fiber,  and  is  gathered  up  by  the  lymph- 
vessels.  One-fourth  of  the  blood  in  the  body  is  in  the  muscles. 

The  nerves  bring  to  each  fiber  its  natural  stimulus  to  action. 

The  work  of  muscle  tissue  is  done  in  the  fiber  cell.  This, 
when  stimulated,  contracts,  bringing  the  two  ends  of  the  fiber 
nearer  to  each  other,  and  naturally  the  fiber  swells  as  it  shortens. 
So  with  the  myriad  of  fibers  in  a  muscle;  when  they  contract,  the 
muscle  swells  and  shortens  (Fig.  98)  illustrates  the  changes  pro- 


FIG.  98. — SHOWING  CHANGE  OF  SHAPE  IN  CONTRACTION. — (Brubaker.) 


duced).  This  results  in  motion,  which  appears  as  the  organs 
attached  are  moved.  One-third  of  the  body  weight  is  muscle 
tissue. 

AlFskeletal  muscles  are  so  attached  as  to  be  tense,  that  is,  they 
are  just  a  little  stretched,  so  that  it  is  easier  for  them  to  act  than 
not.  (A  cut  across  a  muscle  releases  it  from  tension  and  leaves  a 
gaping  wound.)  See  p.  123,  tension  and  tonus. 

The  actions  of  muscles  are  regulated  by  their  attachments,  and 
the  function  is  often  expressed  in  the  name.  If  muscles  or  their 
tendons  pass  in  front  of  a  joint,  for  instance,  causing  flexion,  they 
are  frequently  called  flexors;  or  if  they  pass  behind  such  joints, 
they  may  be  called  extensors;  and  so  with  other  muscles  and  joints. 
Examples:  Flexors  of  the  wrist,  extensors  of  the  fingers,  etc. 
Many  other  examples  will  occur  to  the  student,  as  abductors, 
adductors,  pronators,  etc. 


ACTION    OF   DIAPHRAGM  121 

As  the  location  determines  the  function  of  a  muscle,  so  it  often 
suggests  the  name,  as  the  pectoralis  major  and  minor,  the  inter- 
costals,  etc.  Sometimes  the  shape  is  named,  as  the  orbicularis  of 
the  mouth  or  of  the  eyelids  (orbicular  muscles,  or  sphincters, 
surround  and  control  openings.)  Shape  and  location  may  together 
suggest  a  name  sometimes,  as  the  latissimus  dorsi,  the  rectus 
abdominis  (broadest  of  the  back  and  straight  of  the  ab- 
domen) and  others,  expressing  or  implying  the  function  of  the 
muscle. 

One  of  the  most  useful  and  interesting  muscles  in  the  body  is  the 
diaphragm.  Although  a  voluntary  muscle  in  structure,  it  is  asso- 
ciated with  visceral  action.  (For  general  description  see  page  98.) 

The  special  interest  attending  this  muscle  arises  from  its 
location  as  well  as  its  structure.  Situated  between  the  great 
cavities  of  the  trunk  it  acts  upon  the  organs  belonging  to  both. 
In  contraction,  it  encroaches  upon  the  cavity  of  the  abdomen 
pressing  upon  abdominal  organs,  and  thus  aids  in  expelling  the 
contents  of  abdominal  and  pelvic  viscera.  In  this  act  (expulsion 
from  abdomen  or  pelvis)  it  is  fixed  in  contraction  (holding  the 
breath)  so  that  other  muscles  can  act  efficiently.  Examples: 
defecation,  parturition.  Ceasing  to  contract  it  returns  to  its  inac- 
tive or  dome-shape;  and  as  this  is  accompanied  by  slight  ab- 
dominal pressure  upward,  the  effect  upon  the  thorax  is  to  shorten 
it,  causing  gentle  pressure  upon  the  lungs. 

In  contraction,  therefore,  it  compresses  the  abdomen  and 
enlarges  the  thorax;  in  relaxation,  it  enlarges  the  abdomen  and 
compresses  the  thorax.  This  alternate  enlargement  and  com- 
pression of  the  thorax  explains  its  most  important  function — that 
of  a  breathing  muscle,  especially  a  muscle  of  inspiration. 

Special  points. — The  lateral  portions  of  the  diaphragm  are  the 
most  movable  portions,  being  mostly  muscular.  Here  the  lungs 
rest  upon  the  falling  and  rising  floor,  themselves  alternately  ex- 
panding and  contracting.  The  heart  lies  upon  the  least  movable 
portion — consequently  the  diaphragm  supports  the  heart  but  does 
not  press  against  it  unless  pushed  up  from  below. 

Similar  functions  pertain  to  another  muscle  constituting  the 
floor  of  the  pelvis  (the  levator  ani  and  coccygeus  taken  together), 
which  rises  and  falls  with  the  displacement  and  functionating  of 
abdominal  organs.  With  the  combined  contraction  of  these  two, 


122  ANATOMY   AND    PHYSIOLOGY 

and  relaxation  of  the  diaphragm,  the  whole  body  of  abdominal  and 
pelvic  organs  moves  upward,  and  vice  versa. 

Passing  to  the  consideration  of  more  complicated  movements. 
For  respiration  we  must  have  the  muscles  of  the  thorax;  for 
swallowing  or  deglution,  the  muscles  of  the  tongue  and  throat;  for 
speaking,  those  of  the  tongue  and  face. 

The  arms  and  hands  become  organs  of  prehension  when  by  use 
of  their  numerous  muscles  they  reach  out  to  gather  things  in;  the 
lower  limbs  are  organs  of  locomotion,  only  because  their  muscles 
enable  them  to  bear  and  transport  the  body  from  place  to  place. 
Even  the  ability  to  stand  still  is  due  to  a  balanced  tension  of  mus- 
cles, which  keeps  the  joints  quiet. 

Finally,  various  emotions  may  be  expressed  by  muscle-action 
without  a  spoken  word,  both  by  changes  of  the  face  (referred  to, 
.p.  88)  and  gestures  of  the  body.  Compare  the  erect  posture  of 
the  person  ready  and  alert,  with  the  drooping  figure  of  despond- 
ency or  the  lax  one  of  indolence.  Read  the  meaning  of  the  firm, 
quick  footstep,  and  contrast  it  with  the  uncertain  and  halting 
one.  Note  how  the  hand  may  welcome,  or  repel.  Even  the  eye 
would  be  far  less  expressive  were  the  iris  immovable.  Indeed, 
we  might  well  see  a  literal  meaning  in  the  old  adage — "  Actions 
speak  louder  than  words."  Thus  muscle  action  means  much 
more  than  simple  movement,  and  it  all  depends  ultimately  upon 
the  specially  developed  attributes  of  the  muscle  cell — contractility, 
extensibility,  elasticity. 

And  thus  we  find  that  all  functions  of  the  body  depend  in  the 
beginning  upon  muscle  action,  as  the  heart  itself  is  a  collection  of 
muscles  influencing  the  entire  body,  since  without  circulation  of 
blood  all  processes  of  life  must  cease. 

Muscle  Stimulus. — The  action  of  skeletal  muscles  as  we 
ordinarily  see  them,  expresses  the  result  of  the  response  of  muscle 
tissue  to  the  natural  and  direct  stimulus  of  nerves.  (Nerve  im- 
pulses1 originate  in  the  brain  and  spinal  cord  in  response  to  sense 
impressions,  and  will  be  studied  in  connection  with  the  nervous 
system.)  Certain  other  stimuli  cause  temporary  muscle  action — 
for  example,  the  contact  of  acids  (chemical],  a  sharp  blow  (mechan- 
ical), electricity,  etc. 

Allusion  has  already  been  made  to  the  tension  of  muscles  pro- 

1  An  unsatisfactory  term,  but  in  common  use. 


MUSCLE   TONE  123 

duced  by  the  slight  stretching  of  their  attachments,  as  though  the 
bones  had  outgrown  them  a  very  little.  The  tension  is  in  itself 
a  stimulus,  and  is  increased  by  what  is  called  normal  muscle 
tone. 

Slight  contractions  of  fibers  are  continually  going  on,  caused 
by  various  delicate  stimuli — so  delicate  that  we  are  not  always 
conscious  of  them  although  the  muscle  is;  these  contractions 
constitute  muscle  tone  (tonus)  which  is  important  in  several  ways. 
First,  it  holds  the  muscles  ready  for  instant  action,  making  labor 
easier;  second,  it  maintains  a  steady,  although  slight,  production 
of  body  heat;  third,  it  assists  the  steady  flow  of  circulating  fluids 
—blood  and  lymph;  and  fourth,  it  maintains  favorable  conditions 
in  internal  organs  for  the  processes  of  secretion  and  excretion. 

Although  unconscious  of  normal  muscle  tone,  we  can  often 
recognize  the  increase  of  tone.  One  example  is  the  effect  of 
cold;  shivering  is  an  instance  of  exaggerated  muscle  tone  (it  is 
however  somewhat  complex).  Again,  some  emotions — as  fear, 
anger,  joy,  sorrow,  surprise,  etc.,  always  increase  muscle  tone.  The 
expression  "all  strung  up"  is  in  a  sense  accurate,  if  not  elegant. 
Also,  an  attitude  of  sustained  attention  produces  the  same  effect 
and  is  often  prolonged  to  the  verge  of  conscious  fatigue.  Some 
idea  of  the  degree  of  energy  exerted  in  maintaining  increased  tone 
may  be  derived  from  the  feeling  of  languor  which  follows  it; 
people  often  speak  of  feeling  the  "relaxation"  after  excitement. 

In  all  of  these  conditions,  the  heart  is  quickened  more  or 
less;  and,  in  short,  whatever  cause,  mental  or  physical,  increases 
the  rapidity  of  the  circulation,  will  contribute  to  an  increase  of 
muscle  tone,  by  preserving  nutrition  and  removing  waste  matters. 

Diminished  tone  is  the  result  of  overuse  or  of  poor  nutrition — 
either  of  nerve  or  of  muscle,  or  both- — the  effect  being  a  tired 
feeling,  or  manifesting  itself  in  various  ways,  such  as  inability 
to  work,  physical  and  mental  inefficiency,  etc.  The  need  of  a 
"tonic,"  or  to  be  "toned  up,"  is  a  common  complaint. 

Rest  is  necessary  for  the  restoration  of  muscle  tissue  after  work, 
in  the  ordinary  activities  of  life,  and  still  more  after  excessive 
exercise,  in  order  that  the  renewal  of  muscle  plasma  may 
be  accomplished  and  a  store  of  material  laid  up  for  further 
use.  This  cannot  be  brought  about  while  the  muscle  is  doing 
visible  work. 


124  ANATOMY   AND    PHYSIOLOGY 

Massage  is  beneficial  in  conditions  of  nerve-muscle  tire,  because 
it  improves  the  circulation  while  the  patient  is  in  a  passive  state, 
so  that  better  nutrition  is  secured  and  accumulated  waste  re- 
moved, without  the  necessity  for  effort  by  the  patient.  (The 
same  is  true  of  bruises  and  sprains.)  No  bad  results  will  follow 
moderate  overuse,  provided  sufficient  rest  be  promptly  secured. 
The  expression  "a  healthy  tire"  is  a  logical  one,  because  by 
reasonable  use  a  muscle  grows,  if  suitable  resting  time  is  secured. 
Beyond  a  reasonable  limit,  however,  overuse  is  injurious;  the 
muscles  work  irregularly,  perhaps  painfully;  nutrition  declines; 
wastes  accumulate,  and  the  will  is  no  longer  in  control.  Writer's 
cramp  is  a  familiar  example. 

,The  various  stations  and  postures  of  the  body  are  made 
possible  by  properly  adjusted  muscle  groups,  which  enable  us  to 
preserve  our  balance  in  different  positions.  It  is  here  that  the 
extensibility  and  elasticity  of  muscle  tissue  are  of  greatest  impor- 
tance. Sitting  and  standing,  as  well  as  walking  and  running, 
are  states  of  activity,  whereby  the  flexor  and  extensor  muscles 
(and  associated  groups)  oppose  each  other  in  equilibrium.  It  is 
truly  "hard  work  to  keep  still." 

The  activities  of  muscles  and  nerves  are  so  closely  associated 
that  they  cannot  be  well  understood  apart,  and  will  be  further 
studied  in  Chapters  XX  and  XXI. 

Rigor  Mortis. — It  is  already  stated  that  muscle  fibers  are 
composed  of  muscle  cells ;  the  cell  consists  of  muscle  plasma 
encased  in  a  delicate  substance  called  sarcolemma.  The  plasma 
contains  minute  fibrils  and  various  nutrient  substances,  mostly 
proteins  (page  153).  Upon  the  death  of  the  body  coagulation  of 
muscle  plasma  occurs  and  certain  proteins  are  separated  from  the 
plasma  in  the  form  of  a  clot.  (Myosin  and  Myogen  fibrins.) 
This  coagulation  results  in  a  firm  contraction  of  the  muscle  fibers, 
and  a  general  rigidity,  called  rigor  mortis.  It  appears  first  in  the 
muscles  of  the  lower  jaw,  and,  advancing  downward,  gradually 
involves  the  upper  extremities  and  the  whole  body. 

In  the  case  of  chronic  disease,  or  of  defective  blood  supply, 
the  rigor  appears  soon  (it  may  be  as  early  as  fifteen  minutes)  and 
passes  soon.  After  an  acute  disease  it  appears  late  and  lasts  longer. 

The  disappearance  of  rigor  mortis  is  due  to  the  formation  of 
acids  in  the  muscle  fiber,  which  soften  the  fiber. 


TETANUS,    CRAMP,   FATIGUE 


MUSCLE  TISSUE,  A  SOURCE  or  HEAT  AND  ELECTRICITY 

Thus  far  we  have  considered  only  one  result  of  muscle  action; 
namely,  the  production  of  motion.  Muscle  tissue  is  built  up  of 
food  derived  from  the  blood  —  contraction  means  a  using  up  of  its 
substance,  and  the  formation  of  waste  products.  These  chemical 
processes  are  going  on  continually,  and  all  chemical  action  is  ac- 
companied by  the  production  of  heat.  A  muscle  in  action  is  there- 
fore a  machine  for  producing  body  heat,  and  since  the  muscular 
system  comprises  so  large  a  portion  of  the  human  body  (weighing 
nearly  three  times  as  much  as  the  bones),  it  is  one  of  the  chief 
sources  of  heat;  for  the  double  reason  that  it  includes  a  great  deal 
of  tissue,  and  that  it  is  more  constantly  at  work  than  any  other 
tissue  in  the  body. 

We  all  know  that  the  body  temperature  rises  during  muscular 
exercise;  as  the  vessels  dilate,  bringing  oxygen  for  chemical  action, 
heat  is  rapidly  evolved  and  waste  is  swept  away.  (Blood-  and 
lymph  vessels  carry  both  food  and  waste.) 

In  addition  to  other  results  of  muscle  activity,  a  slight  current 
of  electricity  is  produced,  appreciable  only  by  certain  experiments. 

MODIFICATIONS  OF  MUSCLE  ACTION 

Clinical  notes.  —  Tetanus  is  a  condition  of  the  muscles  in  which 
the  contractions  are  so  rapid  that  the  action  appears  to  be  con- 
tinuous; the  stimuli  come  so  rapidly  that  the  fibers  cannot  perfectly 
relax. 

It  may  be  due  to  various  causes:  to  drugs,  as  strychnine;  to 
bacterial  poisoning  through  invasion  of  wounds  ;  or  to  disordered 
conditions  of  the  nerve  system.  It  may  be  voluntary  in  char- 
acter; when  one  deliberately  stiffens  the  body  or  any  portion  of 
it  the  rigidity  thus  occurring  is  tetanic. 

Cramp  is  sudden  involuntary  contraction  of  muscle-fiber, 
spasmodic  in  character  and  so  violent  as  to  be  exceedingly  painful. 

Convulsive  movements  or  convulsions  (spasms)  are  due  to  invol- 
untary and  forcible  action  of  several  muscles  or  groups  of  muscles. 
The  movements  vary  with  the  number  of  muscles  involved. 

Fatigue  of  muscle  tissue  follows  prolonged  use,  evidenced  by 
sensations  of  pain  in  the  muscles  themselves,  probably  due  to  an 
accumulation  of  waste  matters  when  the  muscle  is  not  quite  equal 


126 


ANATOMY   AND    PHYSIOLOGY 


to  the  demands  made  upon  it;  repair  does  not  keep  pace  with 
wear  and  the  muscle  becomes  not  only  tired  from  overwork  and 
lack  of  food  but  burdened  with  the  poisons  of  fatigue. 


LARGE   MUSCLES   CLASSIFIED   ACCORDING  TO  THEIR  MOST 
FREQUENT  ACTION 


REGION. 


TRUNK 


HEAD 


SHOULDER 
ARM.  . 


FOREARM  . 


ACTION. 


To  enclose  cavities  and  aid 
in  respiration 


To  separate  cavities  and 
aid  in  respiration 

Floor  of  trunk  and  aiding 
above  muscles. . 


To  move  spine  and  trunk 


To  extend  head. 


To  flex  head. . . 
To  rotate  head. 


To  lift  shoulder 

To  pull  shoulder  backward 
To  pull  shoulder  forward. . 

To  pull  arm  forward 

To  pull  arm  backward 

To  abduct  (lift)  arm 


To  adduct  (pull  downward) 
To  rotate  arm,  supination 
To  rotate  arm,  pronation 
To  flex  forearm. . 


To  extend  forearm. . . 
To  rotate,  supination. 


MUSCLES. 


To  rotate,  pronation. 


Intercostals. 
Quadratus  lumborum. 
Obliquus  externus. 
Obliquus  internus. 
Transversus. 
Rectus  abdominis. 

Diaphragm. 

Levator  ani. 

Coccygeus. 

Abdominal  group. 

Erector  spinae. 

Ilio-psoas. 

Erector  spinae. 

Trapezius. 

Sterno-mastoids. 

Trapezius. 

Sterno-mastoid. 

Trapezius. 

Trapezius. 

Anterior  serratus. 

Pectorals. 

Latissimus  dorsi. 

Deltoid. 

Suprascapular. 

Pectorals. 

Latissimus  dorsi. 

Infraspinatus. 

Teres  minor. 

Subscapularis. 

Teres  major. 

Biceps  brachii. 

Brachialis. 

Brachio-radialis. 

Triceps. 

Supinator. 

Biceps  brachii. 

Brachio  radialis. 

Pronator  teres. 

Pronator  quadratus. 


ACTION   OF   MUSCLE   GROUPS 


127 


LARGE  MUSCLES  CLASSIFIED  ACCORDING  TO  THEIR  MOST 
FREQUENT  ACTION—  (Continued) 


REGION. 


ACTION. 


WRIST. 


HAND. 


To  flex  wrist 

To  extend  wrist. 


To  flex  fingers. 


To  extend  fingers. 


MUSCLES. 


To  flex  thumb 

To  extend  thumb . . 


THIGH, 


To  flex  thigh 

To  extend  thigh 

(also  to  extend  trunk) 


To  rotate  outward. 


LEG.. 


To  rotate  inward. . 


To  abduct. . 
To  adduct.. 
To  flex  leg.. 


ANKLE 


To  extend  leg . 


Rotation  outward. 
Rotation  inward. . 
To  flex  ankle. . 


FOOT. 


To  extend  ankle. . 
To  flex  toes. . 


To  extend  toes. 


Flexor  carpi  radialis. 
Flexor  carpi  ulnaris. 
Extensor  carpi  radialis 

(long  and  short). 
Extensor  carpi  ulnaris. 
Flexor   digitorum    (sub- 

lim.). 

Flexor    digitorum    (pro- 
fund.). 
Extensor  digitorum 

(com.). 
Extensors  of  index  and 

little  fingers 
Thenar  group. 
Three   extensors  of 

thumb. 
Ilio-psoas. 
Gluteus  maximus. 
Biceps  femoris. 
Semitendinosus. 
Semimembranosus. 
Glutei-med.  and  min. 
Sartorius. 
Four  adductors. 
Two  obturators. 
Gluteus  min. 
Tensor  fasciae  latae. 
Adductor  magnus  (long 

fibers  of). 
Three  glutei. 
Four  adductors. 
Biceps  femoris. 
Semitendinosus. 
Semimembranosus. 
Sartorius. 
Quadriceps  femoris  (rec- 

tus  and  three  vasti). 
Sartorius. 
Biceps. 
Tibialis  ant. 
Peroneus  tertius. 
Tibialis  post. 
Peronei  (long  and  short). 
Flexor   digitorum 

(longus). 

Flexor  pollicis  (longus). 
Extensor   digitorum 

(longus). 
Extensor  hallucis 

(longus). 


128  ANATOMY  AND   PHYSIOLOGY 

SPINAL  NERVE  SUPPLY  TO  PRINCIPAL  MUSCLE  GROUPS 


REGION. 


SIDE  OF  NECK. 


THORAX  AND  SHOULDER 


MUSCLES. 


NERVE. 


ARM,  ANTERIOR 


ARM,  POSTERIOR 

FOREARM,  POSTERIOR. 


FOREARM,  ANTERIOR. 


HAND. 


ABDOMEN  AND  PELVIS. 


Three  scaleni  muscles. 
Elevator  of  angle  of  scapula 

Intercostal. . . 

Diaphragm 

Sacro-spinalis   (erector 

spinae) 

Latissimus  dorsi 

Supra-  and  infraspinatus.  . 
Subscapularis. 

Teres  major 

Teres  minor 

Deltoid. . 


Pectoralis  major  and  minor 
Biceps. 

Coraco-brachialis 

Brachialis. . 


Triceps 

Supinators  and  extensors 
of  wrist 

Extensors  of  fingers 

Pronators  and  superficial 
flexors 

Flexor  carpi  ulnaris  and 
deep  flexors 

(The  deep  flexor  of  fingers 
has  also  a  branch  from 
median.) 

Thenar  eminence  (muscles 
of  thumb) 

Hypothenar  eminence 
(muscles  of  little  finger) . . 

Interossei 

Rectus  and  pyramidalis. 

Quadratus  lumborum. 

External  and  internal  ob- 
lique. 

Transversus. 

Psoas  and  iliacus 

Levator  ani. 

Perineal  muscles 

Piriformis 

Gluteus  maximus 

Gluteus  medius  and  mini- 
mus. 

Tensor  fasciae  latae 

Obturators,  external  and 
internal.  . 


Cervical  branches  of  bra- 
chial  plexus. 
Intercostal. 
Intercostal  and  phrenic. 

Spinal. 

Long  subscapular. 

Suprascapular . 

Subscapular. 
Axillary. 

Axillary  and    ant.    tho- 
racic. 
Ant.      oracic. 

Musculo-cutaneous. 
Musculo-cutaneous   and 
radial. 


Radial  (musculo-spiral). 
Deep  branch  of  radial. 

Median. 
Ulnar. 


Ulnar  and  median. 

Ulnar. 
Ulnar. 


Thoracic  and  lumbar. 

Pudic. 

Sacral  plexus. 
Inferior  gluteal. 


Superior  gluteal. 
Obturator. 


NERVES  OF  SKELETAL  MUSCLES 


I29 


SPINAL  NERVE  SUPPLY  TO  PRINCIPAL  MUSCLE  GROUPS.— 

(Continued) 


REGION. 


MUSCLES. 


NERVE. 


THIGH Three  adductors. 

Gracilis. . 


THIGH,  ANTERIOR Quadriceps. 


rectus. 
two  vasti. 
crureus. . 


THIGH,  POSTERIOR. 
LEG,  ANTERIOR.  . . . 


LEG,  LATERAL.  .  . 


Biceps. 
Semitendinosus. 

Semimembranosus 

Anterior   muscles   (exten- 
sors)   


Peroneuslongus  andbrevis 


LEG,  POSTERIOR Calf  muscles. 

Deep  muscles  (flexors).. . . 
FOOT Dorsum 

Plantar  region 


Obturator     (sciatic     to 
portion  of  ad.  mag.). 


Femoral   (anterior 
crural). 


Sciatic. 

Deep  peroneal  (anterior 

tibial). 
Superficial  peroneal 

(musculo-cutaneous) . 

Tibial  nerve. 
Deep  peroneal. 
Medial  and  lateral  plan- 
tar. 


CHAPTER  VIII 
THE  ORGANS  OF  DIGESTION 

MOUTH,  PHARYNX,  ESOPHAGUS,  STOMACH,  AND 
INTESTINES 

These,  with  the  glands  which  secrete  the  digestive  fluids,  con- 
stitute the  digestive  apparatus. 


ir \Saliuary  Gland 


--Esophagus 


Spleen 


-  Lacteals 


Large 
Jntestine*   •  - 


Vermiform  Appendix- ~ 


FIG.  99. — GENERAL  SCHEME  OF  THE  DIGESTIVE  TRACT,  WITH  THE  CHIEF  GLANDS 
OPENING  INTO  IT;  TOGETHER  WITH  THE  LACTEALS  ARISING  FROM  THE  INTESTINE 
AND  JOINING  THE  THORACIC  DUCT. — (Landois.) 

The  alimentary  tract  or  canal  is  a  series  of  channels  included 
within  the  organs  named,  constituting  a  long  tube  of  mucous 

130 


DIGESTIVE   FLUIDS,    ENZYMES  131 

membrane  through  which  the  food  passes.  The  glands  which 
secrete  the  digestive  fluids  open  into  this  tract. 

The  digestive  fluid  of  the  mouth  is  saliva. 

The  digestive  fluid  of  the  stomach  is  gastric  juice. 

The  digestive  fluids  of  the  intestines  are  intestinal  juice,  and 
pancreatic  juice  (assisted  by  bile). 

Each  of  these  fluids  contains  one  or  more  of  the  peculiar  sub- 
stances called  enzymes. 

An  enzyme  is  a  ferment  which  by  its  presence  causes  certain 
changes  in  other  substances. 

The  enzymes  of  the  digestive  fluids  cause  the  chemical  changes 
in  food  which  are  necessary  for  its  digestion. 


The  glands  are 


Salivary,  opening  into  the  mouth. 
Peptic,  "     stomach. 

Intestinal,     "         "     intestines. 


Pancreas,  small  intestine. 

Liver,  "     small  intestine. 

The  tongue,  teeth  and  glands  are  appendages  of  the  alimentary  canal. 

THE  MOUTH 

The  mouth,  or  oral  cavity,  is  enclosed  partly  by  muscles  and 
partly  by  bones.  The  muscles  are  the  lip  muscles  in  front,  the 
buccinator  at  the  sides,  and  the  mylo-hyoid  in  the  floor.  The  bones 
are  the  maxilla  and  the  palate-bones  above,  and  the  mandible  below. 

The  roof  of  the  mouth  is  called  the  palate ;  the  bony  portion  is 
the  hard  palate;  the  muscular  portion  attached  to  it  is  the  soft 
palate  or  the  velum  palati  (veil  of  the  palate) .  In  the  middle  of  the 
soft  palate  is  the  uvula,  which  is  a  small  projection  downward. 
All  of  these  bones  and  muscles  are  in  pairs,  right  and  left. 

Surgical  note. — If,  owing  to  lack  of  development  they  are  not  joined  in 
the  middle  line,  cleft  palate  results.  The  cleft  may  be  partial  or  complete, 
and  the  divided  upper  lip  is  called  harelip. 

The  oral  cavity  is  lined  with  mucous  membrane  which  is  always 
moist  in  health.  The  part  of  the  cavity  between  the  lips  and  the 
teeth  is  the  vestibule. 

The  mouth  contains  the  teeth  and  the  tongue. 

The  teeth  are  already  described. 

The  tongue  lies  in  the  floor  of  the  mouth  with  its  base  curved 
downward  at  the  back  and  attached  to  the  hyoid  bone.  It  is 
composed  of  muscles,  and  covered  with  mucous  membrane  which 


132 


ANATOMY   AND    PHYSIOLOGY 


forms  a  special  fold  underneath  the  tip  of  the  tongue  connecting 
it  with  the  floor;  this  fold  is  called  the  frenum  lingua.  When  the 
frenum  is  short  we  say  the  tongue  is  "tied." 

A  little  clip  with  the  scissors  is  often  sufficient  to  free  it,  but  this  is  done 
with  care  as  an  artery  runs  forward  very  near  the  frenum. 


Septum . 

Nostril 


Anterior  naris 


Hard  palate 


Anterior  palatine 

arch 

Recess 
Posterior  palatine 

arch 


Tongue 


FIG.  ioo. — THE  ORAL  CAVITY. — (Deaver.) 

The  dor  sum,  or  superior  surface  of  the  tongue,  is  covered  with 
small  projections  called  papilla,  of  three  sizes— the  vallate,  the 
largest,  forming  a  V-shaped  row  at  the  back;  the  fungiform,  next 
in  size,  scattered  over  the  surface  but  most  numerous  at  the  tip  and 
sides,  and  bright  red  in  color;  and  the  filiform,  the  smallest,  cover- 
ing the  anterior  two-thirds  of  the  dorsum  and  borders  (Fig.  101). 

The  tongue  aids  in  mastication  and  swallowing,  or  deglutition. 
It  is  also  an  important  organ  of  speech  and  the  principal  organ  of 
taste. 


THE    MOUTH 


133 


Note. — The  perception  of  bitter  substances  is  plainer  in  the  posterior 
portion,  while  sweet,  sour,  and  salty  substances  are  more  quickly  recognized 
in  the  anterior  part  and  at  the  borders.  The  nerves  of  taste  are  in  the  papillae. 

Some  elevations  of  mucous  membrane  on  either  side  of  the  base  of  the 
tongue  form  the  lingual  tonsils.  (These  are  seen  only  with  the  aid  of  the 
laryngoscope.).  They  contain  lymphoid  tissue. 


Parotid 
gland 


Masseter 
muscle 


Floor  of  mouth  and  sub  ,  ,  

maxillary  duct  /  \m  — -Hyoidbone 

Submaxillary  gland 

(main  portion  is  drawn  backward) 

FIG.  10 1. — SALIVARY  GLANDS  AND  PAPILLA  OF  TONGUE. — (Morris.) 

The  mouth  opens  at  the  back  into  the  pharynx,  through  the 
passage  called  the  isthmus  of  the  fauces.  This  passage  is  bounded  by 
two  folds  on  each  side  running  downward  from  the  soft  palate  and 
called  the  palatine  arches,  or  pillars  of  the  fauces.  B  etween  the  anter- 
ior and  posterior  arch  of  either  side  is  the  palatine  tonsil,1  a  gland- 
like  body  the  use  of  which  is  not  clearly  understood2  (Fig.  100). 

It  presents  small  openings  upon  its  surface  leading  into  recesses  or  crypts 
which  are  surrounded  by  the  follicles  of  the  tonsils. 

Clinical  note. — Follicular  tonsillitis  is  an  inflammation  of  the  mucous 
membrane  and  follicles  in  the  crypts. 

lFaucial  tonsil. 

2  The  student  may  see  all  of  these  structures  by  examining  her  own  mouth  with 
the  aid  of  a  hand-mirror  and  a  good  light. 


134  ANATOMY  AND   PHYSIOLOGY 

Salivary  glands. — The  digestive  fluid  of  the  mouth  is  called 
saliva.  It  is  secreted  by  the  salivary  glands,  three  in  number  on 
each  side — the  parotid,  submaxillary,  and  sublingual  (Fig.  101). 

The  parotid  gland  is  situated  in  front  of  and  below  the  ear, 
and  has  a  duct  about  two  inches  long  (Stenson's  duct)  which  runs 
forward  to  open  into  the  mouth  opposite  the  second  molar  tooth 
of  the  upper  jaw,  piercing  the  buccinator  muscle.  It  secretes  an 
abundant  watery  fluid. 

The  surface  line  of  Stenson's  duct  is  drawn  from  the  lobe  of  the  ear  to  the 
middle  of  the  upper  lip. 

The  submaxillary  gland  lies  under  the  angle  of  the  jaw,  open- 
ing into  the  floor  of  the  mouth  close  to  the  f renum,  by  Wharton  ys 
duct.  It  secretes  a  thicker  fluid  than  the  parotid  gland. 

The  sublingual  gland  lies  in  the  (anterior)  floor  of  the  mouth 
and  opens  under  the  tongue  near  the  frenum,  by  several  small 
ducts.  This  also  secretes  a  thicker  fluid. 

The  fluid  which  is  constantly  present  in  the  mouth  and  com- 
monly called  saliva,  is  a  mixture  of  the  secretion  of  the  salivary 
glands  and  the  mucous  glands  of  the  mouth. 

The  reaction  of  the  saliva  is  alkaline.  The  enzymes  or  ferments 
of  saliva  are  ptyalin  and  maltase.  The  average  daily  quantity 
of  mixed  saliva  is  1400  gm. 

THE  PHARYNX 

The  pharynx,  or  throat,  receives  the  food  from  the  mouth.  It 
occupies  a  space  in  front  of  the  spinal  column  from  the  base  of  the 
skull  to  the  fifth  cervical  vertebra,  its  roof  being  formed  by  the 
body  of  the  sphenoid  bone,  joined  to  the  occipital.  The  walls  of  the 
pharynx  consist  of  three  pairs  of  muscles  called  the  constrictors— 
upper,  middle,  and  lower,  strengthened  by  a  fibrous  layer  and 
lined  with  mucous  membrane. 

The  illustration  shows  that  the  constrictors  are  flat  muscles  attached  at 
the  sides  to  the  structures  in  front  of  the  pharynx.  Thus,  from  above  down- 
,  ward,  their  origin  is  on  the  pterygoid  process,  a  special  ligament,  the  mandible, 
side  of  the  tongue,  hyoid  bone,  thyroid  and  cricoid  cartilages.  The  fibers  all 
join  a  fibrous  line,  or  raphe,  at  the  back,  which  is  suspended  from  the  base 
of  the  occipital  bone.  This  is  their  insertion. 

By  due  contraction  of  these  muscles  the  food  is  grasped  and 
pressed  downward  into  the  esophagus.  They  are  composed  of 
striated  or  voluntary  muscle  fibers. 


OPENINGS    OF    PHARYNX 


135 


The  upper  part  of  the  pharynx  is  behind  the  nose  and  is  called  the 
nasal  part,  ornaso-pharynx.  The  middle  part  is  behind  the  mouth 
and  is  called  the  oral  part,  or  oro-pharynx.  (It  is  this  part  which  we 
see  when  looking  directly  into  the  throat.)  The  lower  part  is  behind 
the  larynx  and  is  called  the  laryngeal  part,  or  the  laryngo-pharynx. 

The  openings  of  the  pharynx  are  seven  in  number:  the  two 
choana  (posterior  nares)  communicating  with  the  nose;  the  two 


Orbic.  oris  muscle 


Special  ligament 


Mylo-hyo'd  muscle 

TTvoid  bon 

Thyro-hyoid 

membrane ; 

Thyroid  cartilage 


Cricoid  cartilage 
Trachea 


Esophagus 


FIG.  102. — THE  PHARYNX. — (Holden.) 

auditory  (Eustachian)  tubes  communicating  with  the  ears,  and  the 
isthmus  of  the  fauces,  communicating  with  the  mouth.  Below,  it 
communicates  with  the  larynx  (the  opening  being  guarded  by  the 
epiglottis)  and  opens  into  the  esophagus. 

The  food  passes  through  the  oro-pharynx  and  laryngo-pharynx, 
the  naso-pharynx  being  an  air-passage. 

In  the  roof  of  the  pharynx  is  a  small  mass  of  lymphoid  tissue  called  the 
pharyngeal  tonsil.     If  hypertrophied  it  forms  an  adenoid  tumor  or  "adenoid" 

THE  ESOPHAGUS 

The  esophagus  (Figs.  102,  99)  begins  at  the  lower  end  of  the 
pharynx  and  extends  downward  in  the  neck  in  front  of  the  spinal 


136 


ANATOMY  AND   PHYSIOLOGY 


column,  to  pass  into  the  thorax.  It  finally  comes  forward  in 
front  of  the  aorta,  passes  through  the  diaphragm,  and  terminates 
in  the  stomach.  It  is  a  tube  about  nine  inches  long,  having  two 
layers  of  muscles  (circular  within,  longitudinal  without)  and  lined 


JJ 

FIG.  103. — SHOWING  SITUATION  OF  PHARYNX  BEHIND  NOSE,  MOUTH,  AND  LARYNX 

— (From  Dealer's  "Surgical  Anatomy .") 

a,~b,  c,  dj  e,  Turbinal  bones  and  meatuses  of  the  nose;  g.i,  tongue;  h,  posterior 
palatine  arch;  y,  anterior  palatine  arch;  k,  hyoid  bone;.;,  mylo-hyoid  muscle  (floor  of 
mouth);  m,  thyro-hyoid  membrane;  n,  ventricle  of  larynx;  p,  q.  r,  sphenoid  bone  and 
sphenoidal  sinus;  v,  hard  palate;  w,  soft  palate;  x,  uvula;  z,  tonsil;  t,  naso-pharynx;  u, 
orifice  of  auditory  tube;  aa,  oro-pharynx;  dd,  laryngo-pharynx;  bb,  epiglottis;  ee, 
upper  portion  of  larynx;  gg,  vocal  bands;  /,  false  vocal  bands;  hh,  lower  part  of 
larynx;  ii,  cricoid  cartilage;  jj,  trachea. 

with  mucous  membrane.     By  contraction  of  the  different  muscles 
from  above  downward  the  food  is  passed  along  to  the  stomach. 

The  esophagus  lies  at  first  immediately  behind  the  trachea. 
The  upper  part  is  composed  of  striated,  or  voluntary  muscle  like 
that  of  the  pharynx;  in  the  lower  part  the  muscle  is  non-striated, 
or  involuntary,  like  the  stomach. 


THE   STOMACH  137 

At  the  termination  in  the  stomach,  the  circular  fibers  are  most 
numerous,  forming  the  cardiac  sphincter  which  prevents  the  return 
of  stomach  contents. 

The  remaining  organs  of  digestion  are  contained  in  the  ab- 
dominal cavity,  which  is  lined  with  a  serous  sac  or  membrane 
called  peritoneum  (see  p.  367).  These  organs  are  developed  from 
an  original  straight  tube  behind  the  peritoneum.  Therefore, 
as  they  grow,  they  press  forward  against  it  and  get  a  covering 
which  is  called  their  serous  layer.  Their  muscular  coats  are  all 
involuntary  or  unstriped  muscle. 

THE  STOMACH 

The  stomach  (gaster,  Fig.  104)  is  in  the  epigastric  region  of  the 
abdomen  just  below  the  diaphragm.  Shape  and  size:  like  a 
curved  flask,  ten  to  twelve  inches  long  and  six  to  eight  wide  at 
the  larger  end,  which  is  turned  toward  the  left  side.  Average 
capacity:  five  pints  in  distention;  two  pints  when  moderately  filled. 

The  stomach  has  two  surfaces,  two  borders,  two  orifices  and  two 
extremities — cardiac  and  pyloric,  with  a  pre-pyloric  part  between 
them. 

The  surfaces  are  the  anterior — looking  slightly  upward;  and  the 
posterior — looking  slightly  downward. 

The  borders  are  usually  called  curvatures;  the  upper  border  is 
the  lesser  curvature  (about  five  inches  in  length) ;  the  lower  border  is 
the  greater  curvature  (about  twenty  inches  in  length) . 

The  left  extremity  is  the  expanded  portion  called  ihefundus  of 
the  stomach  (also  the  greater  cul-de-sac) ,  and  the  cardiac  end  (from 
its  nearness  to  the  heart). 

The  right  extremity  is  called  the  pyloric  extremity.  It  is  just 
below  the  liver. 

The  orifices  are  at  the  extremities.  At  the  left  is  the  esopha- 
geal  orifice,  guarded  by  the  sphincter  of  the  cardia;  at  the  right 
is  the  pyloric  orifice,  guarded  by  the  sphincter  of  the  pylorus  or 
"gate-keeper." 

The  coats  or  tunics  of  the  stomach  are  four  in  number— 
mucous,  submucous,  muscular,  and  serous. 

The  mucous  layer,  or  mucosa,  is  the  innermost  layer.  It  is 
pink  in  color  but  becomes  bright  red  when  food  is  present,  from  the 
increased  blood-supply  necessary  for  digestion.  It  lies  in  folds,  or 


138 


ANATOMY  AND   PHYSIOLOGY 


rugae,  running  from  one  extremity  to  the  other — the  longitudinal 
folds.  This  layer  contains  the  gastric  glands  which  secrete  the 
gastric  juice  and  pour  it  through  their  ducts  into  the  stomach. 

The  submucous  layer  or  submucosa  is  a  network  of  connective 
tissue  next  to  the  mucous  coat.  It  bears  fine  vessels,  nerves  and 
lymphatics,  and  connects  the  mucous  and  muscular  tunics  together 
loosely,  so  that  when  the  stomach  is  distended  the  longitudinal  folds 
simply  disappear,  without  injury  to  the  mucous  membrane. 

The  muscular  coat  (or  tunic]  comprises  three  layers  of  non- 
striated  muscle:  internal,  middle  and  external.  The  internal  layer 


Aorta 


CeLac  artery 

Gastric  artery 


FIG.  104. — THE  STOMACH  AND  SPLEEN. — (Morris.} 

consists  of  oblique  fibers  (it  is  a  thin  layer  and  is  mostly  con- 
fined to  the  cardiac  portion).  The  middle  layer  is  a  complete 
layer  of  circular  fibers.  They  are  most  numerous  at  the  ex- 
tremities of  the  stomach,  where  they  form  two  ring-shaped 
bundles.  One  is  the  sphincter  of  the  cardia,  surrounding  the  lower 
end  of  the  esophagus  and  the  cardiac  orifice  of  the  stomach;  the 
other  is  the  sphincter  of  the  pylorus,  which  is  a  strong  ring-muscle 
diminishing  the  size  of  the  pyloric  orifice  so  that  it  is  the  narrowest 
portion  of  the  alimentary  tract  (a  half-inch,  or  3  mm.).  The  ex- 
ternal layer  consists  of  longitudinal  fibers  (fibers  running  length- 


THE   INTESTINE 


139 


wise)  which  are  continued  from  the  similar  layer  of  the  esophagus, 
and  pass  on  to  those  of  the  intestine. 

The  serous  coat  (or  tunic)  is  a  portion  of  the  great  serous  mem- 
brane of  the  abdomen,  called  the  peritoneum  (page  367).  The 
two  surfaces  of  the  stomach  are  covered  by  different  layers  of  per- 
itoneum which  will  be  described  elsewhere  (Fig.  in  and  p.  148). 

The  gastric  glands  are  embedded 
in  the  mucosa.  They  are  tubular  in 
form,  microscopic  in  size,  and  very 
numerous  (their  number  is  estimated 
at  5,000,000).  They  differ  markedly 
in  the  two  portions  of  the  stomach. 
The  cardiac  glands  secrete  the  diges- 
tive ferments,  pepsin  and  rennin, 
while  the  pyloric  glands  secrete  mucus 
also  (Fig.  105). 

The  reaction  of  the  gastric  juice  is 
acid  (owing  to  hydrochloric  acid). 
This  acid  is  a  natural  but  not  a 
powerful  antiseptic. 

The  position  of  the  stomach  is 
oblique,  the  pyloric  end  being  on  a 
lower  level  than  the  cardiac.  It  is  also  the  movable  end. 

The  location  of  the  stomach  is  mostly  in  the  epigastric  region 
(Fig.  235).  It  is  below  the  portion  of  the  diaphragm  which 
supports  the  heart;  behind  it  are  the  largest  artery  and  vein  in  the 
body — the  aorta  and  the  inferior  vena  cava.  The  pyloric  end  ex- 
tends under  the  liver  in  the  right  hypochondrium,  while  the  cardiac 
end  is  in  contact  with  the  spleen  in  the  left  hypochondrium. 

Clinical  notes. — When  the  stomach  is  empty  it  tends  to  a  vertical  position 
when  filled,  it  swings  upward  and  forward  to  become  again  oblique.  If 
much  distended,  as  with  gas,  it  embarrasses  the  action  of  the  heart  by  pressure. 

The  infant's  stomach  is  nearly  or  quite  vertical  and  easily  overflows;  its 
capacity  at  birth  is  one  ounce,  reaching  two  ounces  at  about  the  end  of  a 
fortnight  and  eight  ounces  at  ten  or  eleven  months. 

THE  INTESTINE 

The  intestine  or  bowel  begins  at  the  pyloric  orifice  of  the 
stomach  and  continues  to  the  end  of  the  alimentary  tract.  It  is 
from  twenty-five  to  thirty  feet  in  length  (Fig.  106). 


FIG.  105. — SECTION  OF  PYLORIC 
GLANDS  FROM  HUMAN  STOMACH. 
a.  Mouth  of  gland  leading 
into  long,  wide  duct  (&),  into 
which  open  the  terminal  divi- 
sions, c.  Connective  tissue  of 
the  mucosa. — (After  Pier  sol.) 


140 


ANATOMY  AND   PHYSIOLOGY 


Like  the  stomach,  it  is  composed  of  four  coats  or  tunics — 
mucous,  submucous,  muscular  and  serous. 

The  mucous  coat  is  the  glandular  coat;  that  is,  the  glands  which 
secrete  intestinal  juice  are  imbedded  in  the  mucous  coat,  and  their 
ducts  open  on  its  surface. 


Vessels  | 
of  large 
intestine  | 


Cecum 


Appendix 


FIG.  106. — THE  INTESTINES. — (Morris.) 
Large  intestine  thrown  upward,  small  intestine  drawn  to  left. 

In  addition,  small  gland-like  bodies  of  lymphoid  structure  are  scattered 
throughout  this  coat.  They  have  no  ducts.  They  are  probably  lymph 
nodules — the  so-called  solitary  glands. 

The  submucous  coat  bears  the  fine  vessels  and  nerves  which 
supply  the  mucous  coat.  It  connects  the  mucous  and  muscular 
coats  together. 


THE   SMALL  INTESTINE  141 

The  muscular  coat  comprises  two  layers  (like  the  esophagus), 
an  inner  layer  of  circular  fibers,  an  outer  one  of  longitudinal 
fibers. 

The  intestine  is  divided  into  the  following  parts: 

Duodenum  f  Cecum 

(  Ascending 

Small  intestine      Jejunum          Large  intestine    {  Colon  Transverse 

(  Descending 

Ileum  I  Rectum 

The  Small  Intestine 

The  small  intestine  is  about  twenty  feet  in  length,  and  about 
two  inches  wide  in  its  upper  (widest)  part.  It  extends  from  the 
stomach  to  the  colon,  beginning  with  the  pyloric  sphincter  in  the 
right  hypochondrium  and  ending  with  the  ileo-colic  sphincter  in 
the  right  iliac  region. 

The  mucous  coat  of  the  small  intestine  forms  circular  folds 
(old  name,  valvulae  conniventes)  which  are  permanent,  that  is, 
they  never  disappear  however  widely  the  bowel  may  be  distended. 
They  serve  to  increase  the  area  of  mucous  membrane  for  purposes 
of  digestion  and  absorption  (Fig.  108).  This  layer  contains  the 
intestinal  glands. 

The  entire  mucous  coat  is  covered  with  tiny  projections  hair- 
like  in.  size  (from  1/2  to  i  mm.  long)  called  villi,  which  give  it  a 
velvety  appearance  (Fig.  107). 

The  villi  are  absorbing  structures  or  absorbents.  (They  may 
be  demonstrated  in  a  good  light  by  laying  a  piece  of  intestinal  wall 
in  a  shallow  tray  of  clear  water;  the  water  will  float  their  free 
extremities.) 

In  the  midst  of  each  villus  is  a  minute  lymph  capillary,  surrounded  by  a 
fine  network  of  blood-vessels  and  lymph  spaces,  the  whole  covered  by  a  layer 
of  the  special  epithelium  of  the  intestine.  Lymph  vessels  of  villi  are  called 
lacteals  because  during  digestion  they  contain  a  milky-looking  fluid. 

The  muscular  coat  is  in  two  layers — circular  within,  longitudinal 
without — pretty  evenly  distributed. 

The  serous  coat  covers  all  except  a  portion  of  the  first  division 
(see  duodenum). 

The  duodenum  is  the  first  division  of  the  small  intestine 


142 


ANATOMY   AND   PHYSIOLOGY 


(Fig.  109).  It  begins  at  the  pyloric  end  of  the  stomach  and 
is  about  ten  inches  long;  curves  upward,  backward,  to  the  right 
and  downward,  and  then  continues  across  to  the  left  side  of  the 

spinal  column. 

About  four  inches  from  the 
pylorus  the  mucosa  presents  an 
elevation — the  bile  papilla, 
where  the  common  bile  and 
pancreatic  duct  opens. 

The  circular  folds  of  the 
mucous  coat  begin  in  the  lower 
portion  and  are  unusually  large. 


FIG.  107. — SECTION  OF  INJECTED  SMALL  FIG.  108. — CIRCULAR  FOLD  OR  VAL- 

INTESTINE  OF  CAT.  VUL.E   CONNIVENTES. —  (Brinton.) 

a,  b.  Mucosa.  g.  Villi.  i.  Their  absorbent 
vessels,  h.  Simple  follicles,  c.  Muscularis 
mucpsae.  j.  Submucosa.  g£.  Circular  and 
longitudinal  layers  of  muscle.  /.  Fibrous 
coat.  All  the  dark  lines  represent  blood- 
vessels filled  with  the  injection  mass. 
— (Piersol) 

Note. — The  inferior  part  of  the  duodenum  is  behind  the  peritoneum,  this 
part  has  no  serous  coat. 

The  jejunum  is  the  second  division  of  the  small  intestine— 
so  named  because  it  is  found  empty.  It  possesses  all  of  the  char- 
acteristic structures:  villi,  circular  folds,  intestinal  and  solitary 
glands.  It  lies  in  the  umbilical  and  the  two  lumbar  regions. 

The  ileum  is  the  third  division  of  the  small  intestine — so 
named  because  of  its  frequent  twisting.  There  is  no  definite 


THE   ILEUM 


143 


separation  between  the  end  of  the  jejunum  and  the  beginning  of 
the  ileum. 

The  mill  and  circular  folds  are  all  found  throughout  the  ileum. 

The  ileum  ends  in  the  right  iliac  region  by  opening  into  the 
large  intestine.  This  orifice  is  doubly  guarded;  first,  by  two  folds 
of  mucous  membrane  strengthened  by  fibrous  tissue,  called  the 
ileo-cecal  valve;  second,  by  a  circular  muscle  called  the  ileo-colic 
sphincter;  this  is  the  more  important  of  the  two. 


13 


277 


FIG.  109. — LIVER,  PANCREAS,  DUODENUM,  SPLEEN  AND  KIDNEYS,  i,  2,  3. 
Duodenum.  4,  4,  5,  6,  7,  7,  8.  Pancreas  and  pancreatic  ducts.  9,  10,  n,  12,  13. 
Liver.  14.  Gall  bladder.  15.  Hepatic  duct.  *  16.  Cystic  duct.  17.  Common 
duct.  18.  Portal  vein.  19.  Branch  from  the  celiac  axis.  20.  Hepatic  artery.  21. 
Coronary  artery  of  the  stomach.  22.  Cardiac  portion  of  the  stomach.  23.  Splenic 
artery.  24.  Spleen.  25.  Left  kidney.  26.  Right  kidney.  Section  of  pancreas 
to  show  ducts.  Liver  turned  upward  and  stomach  removed  to  show  duodenum. 
— (Sappey.) 

The  secreting  glands  of  the  small  intestine  are  embedded  in  the 
mucosa,  and  are  found  in  every  part.  They  are  called  the  in- 
testinal glands  or  intestinal  foLicles,  or  glands  of  Lieberkuhn. 
They  are  tubular  in  shape,  and  secrete  the  greater  portion  of 
the  so-called  intestinal  juice.  The  ferments  of  the  glands  are  erep- 
sin,  iwuertase,  maltase,  etc.  The  reaction  of  the  fluids  is  alkaline. 

In  addition  to  the  above,  there  are  small  round  bodies  called 
solitary  glands.  They  increase  in  size  in  the  lower  end  of  the 
ileum  where  they  are  grouped  in  oblong  patches — the  Peyer's 


144  ANATOMY  AND   PHYSIOLOGY 

patches  (or  agminated  glands)  the  largest  of  which  may  measure 
three  inches  in  length. 

Clinical  note. — The  solitary  glands  (more  especially  the  Peyer's 
patches)  become  inflamed  and  ulcerated  in  typhoid  fever. 

The  Large  Intestine 

The  large  intestine  is  about  five  feet  long  and  two  and  one-half 
inches  wide  in  the  widest  part.  It  begins  where  the  small  intestine 
ends  (in  the  right  iliac  region) ,  ascends  through  the  right  lumbar, 
crosses  the  abdomen  in  front  of  the  small  intestine,  descends  to 
the  left  iliac  region,  and  thence  down  through  the  pelvis,  ending  in 
front  of  the  coccyx.  (See  Regions  of  the  Abdomen,  p.  366.) 

The  mucous  coat  is  smooth  and  rather  pale.  No  folds  are 
present,  and  no  villi,  but  the  solitary  and  tubular  glands  are 
numerous,  like  those  of  the  small  intestine. 

The  circular  fibers  of  the  muscular  coat  are  evenly  distributed, 
but  the  longitudinal  fibers  of  the  cecum  and  colon  are  arranged  in 
three  bands,  placed  at  even  distances  apart.  These  bands  are 
shorter  than  the  tube  itself,  therefore  they  gather  it  into  puffs 
which  give  the  bowel  a  sacculated  appearance.  By  this,  the  large 
bowel  may  be  recognized  at  once,  even  should  it  be  really  small 
in  actual  size  in  some  portion  of  its  extent. 

The  serous  coat  covers  the  greater  part  of  the  large  intestine; 
the  exceptions  will  be  noted  later.  (See  p.  146,  Surgical  Note, 
The  Rectum.) 

The  four  divisions  of  the  large  intestine  are  the  cecum,  the 
colon,  the  sigmoid  loop,  and  the  rectum  (Figs.  106,  no). 

The  cecum,  or  first  division ,  is  a  short  pouch  hanging  below  the 
level  of  the  ileocolic  valve  and  presenting  the  opening  of  the  appen- 
dix vermiformis  or  appendix  ceci.  The  three  longitudinal  bands 
of  the  muscular  coat  meet  at  the  base  of  the  appendix,  which  is  a 
small  tube  three  or  four  inches  long,  attached  to  the  posterior  wall 
of  the  cecum.  It  often  turns  upward,  quite  as  often  downward, 
and  may  lie  transversely.  It  has  all  four  coats,  with  intestinal 
and  solitary  glands,  but  is  of  no  use. 

Clinical  note. — Owing  to  its  small  size  any  substance  which  enters  the 
appendix  is  apt  to  be  retained,  and  if  it  is  of  an  injurious  character  it  will 
cause  appendicitis.  This  disease  is  more  often  caused  by  the  action  of 


THE    COLON 


145 

Small  intestinal  worms 


harmful  bacteria  than  the  celebrated  cherry-stone. 
have  been  found  within  the  appendix. 

The  ilio-cecal  valve  consists  of  two  folds  of  mucous  membrane 
with  muscle  fibers  between  the  layers.     They  are  placed  at  the  end 


FIG.  no. — THE  LARGE  INTESTINE. 

The  small  intestine  and  its  vessels  are  drawn  to  the  right  to  show  the  sigmoid  colon 
and  the  rectum.     The  transverse  colon  is  thrown  upward. — {Morris.) 

of  the  ilium  where  it  opens  into  the  colon,  and  project  toward  each 
other,  leaving  only  a  slit-like  passage. 

The  colon  begins  at  the  ilio-cecal  valve.  The  first  part,  or 
ascending  colon,  passes  upward  in  the  right  lumbar  region.  After 
making  a  bend  under  the  liver — the  right  colic  flexure  (or  hepatic 
flexure),  it  becomes  the  transverse  colon,  which  hangs  in  a  loop  across 
the  abdomen  in  front  of  the  small  intestine.  Another  bend  occurs 
under  the  spleen,  the  left  colic  flexure  (or  splenic  flexure) ;  thence 
the  descending  colon  passes  downward  in  the  left  lumbar  region  to 
the  left  iliac  fossa.  Here  it  makes  an  S-shaped  or  sigmoid  bend 


146  ANATOMY  AND   PHYSIOLOGY 

and  becomes  the  so-called  sigmoid  colon.     It  then  enters  the  pelvis 
to  become  the  rectum. 

Surgical  note. — The  ascending  colon  lies  so  close  to  the  posterior  abdominal 
wall  that  there  is  no  peritoneum  behind  it,  and  the  descending  colon  also  is  bare 
in  a  narrow  strip  at  the  back,  consequently  the  surgeon  may  take  advantage  of 
this  condition  to  open  the  colon  without  wounding  the  peritoneum,  in  the 
operation  called  lumbo-colotomy. 

The  rectum  is  about  five  to  seven  inches  long,  very  distensible, 
and  so  called  because  it  has  no  convolutions,  but  simply  follows  the 
curve  of  the  pelvic  wall,  lying  in  front  of  the  sacrum  and  coccyx. 
In  the  last  inch  or  inch  and  a  half  it  bends  backward  (perineal 
flexure)  to  pass  the  tip  of  the  coccyx.  This  is  the  anal  canal,  and 
it  ends  at  the  opening  called  the  anus  (Fig.  no). 

The  portion  above  the  anal  canal  is  the  widest  part — the  rectal 
pouch. 

The  mucous  membrane  of  the  rectum  is  red,  and  usually  pre- 
sents two  or  three  special  folds  about  two  or  three  inches  above  the 
anus,  called  the  rectal  folds,  or  Houston's  valves. 

The  largest,  a  permanent  fold,  is  on  the  right  side  about  two  and  one-half 
inches  above  the  anus  and  called  the  third  sphincter.  Two  smaller  ones,  not 
permanent,  are  on  the  left  side,  above  and  below  the  former. 

The  muscular  coat  has  the  two  layers,  circular  and  longitudinal. 
The  peritoneal  coat  covers  the  front  and  sides  of  the  upper  part  only. 

The  reaction  of  the  fluids  in  the  large  intestine  is  alkaline. 

Sphincters  of  the  anus. — The  circular  fibers  around  the  anal 
canal  form  the  internal  sphincter. 

The  external  sphincter  is  a  flat  circular  muscle  just  under  the 
skin  around  the  anus.  (Its  contraction  causes  the  radiating  lines 
in  the  skin.)  The  function  of  the  sphincters  is  to  guard  and 
control  the  anus. 

Clinical  note. — The  point  of  a  syringe  should  be  passed  in  an  upward  and 
forward  direction  through  the  anal  canal,  and  then  turned  backward, 

RESUME. 

The  alimentary  tract  begins  with  the  mouth  and  ends  with  the  large  in- 
testine, passing  through  the  head,  neck,  thorax,  and  pelvis.  It  is  practically 
a  long  tube  of  mucous  membrane  surrounded  by  layers  of  muscle  and  held  to 
them  by  connective  tissue.  The  mucous  membrane  contains  glands  which 
secrete  the  digestive  fluids.  The  muscle  layers  pass  the  food  along,  that  it  may 
be  acted  upon  in  all  portions  of  the  tract;  and  wherever  free  motion  accom- 


THE   MESENTERY 


panics  the  digestion  of  the  food,  a  serous  layer  is  added  outside  of  all  to  prevent 
friction. 

The  digestive  fluid  of  the  stomach  is  acid;  in  all  other  parts  it  is  alkaline. 

Peristalsis  is  the  name  given  to  the  peculiar  motion  of  the 
stomach  and  intestine  during  the  passage  of  their  contents.  The 
circular  fibers  compress  the  food  and  at  the  same  time  the  longi- 
tudinal fibers  shorten  the  tube.  This  action  goes  on  from  above 
downward,  causing  a  sort  of  worm-like  movement  which  is  de- 
scribed as  peristalsis,  or  peristaltic  movement. 


Liver 

Gastro-hepatic  omentum 
Stomach 

Transverse  colon 

M  esentery 

Small  intestine 

Uterus 


Epiploic  foramen 
Pancreas 

Duodenum 

Transverse  meso-colon 
Aorta 


Rectum 


Bladder 


FIG.  in — DIAGRAM  OF  A  SAGITTAL  SECTION  or  THE  TRUNK,  SHOWING  THE  RELA- 
TIONS OF  THE  PERITONEUM. — (Allen  Thompson.} 

The  mesentery  is  the  fold  of  peritoneum  which  holds  the 
jejunum  and  ileum  in  place.  This  fold  leaves  the  posterior  ab- 
dominal wall  at  a  line  inclining  downward  to  the  right,  about  five 
or  six  inches  long;  but  it  includes  twenty  feet  of  intestine,  and 
therefore  it  is  like  a  very  full  ruffle  twenty  feet  in  length  with  a 
band  of  six  inches.  The  vessels  and  nerves  of  the  intestine  lie 
between  the  layers  of  the  mesenteric  fold. 

Any  fold  of  peritoneum  which  connects  a  portion  of  intestine  to  the  wall  of 
the  trunk  is  a  mesentery.  The  meso-colon  connects  the  colon  with  the  abdom- 


148  ANATOMY   AND   PHYSIOLOGY 

inal  wall;  the  meso-rectum  connects  the  rectum  with  the  pelvic  wall;  the 
large  mesentery  holds  the  ileum  and  jejunum  to  the  posterior  abdominal  wall. 

An  omentum  is  a  fold  of  peritoneum  connected  with  the  stomach.  The 
greater  omentum  hangs  from  the  greater  curvature;  the  lesser  omentum  connects 
the  lesser  curvature  with  the  liver  (being  called  the  gastrohepatic  omentum); 
and  the  gastro splenic  omentum  connects  the  stomach  and  spleen.  (Two 
layers  of  peritoneum  pass  from  the  under  surface  of  the  liver  to  the  lesser 
curvature  of  the  stomach,  forming  the  lesser  omentum.  They  then  separate 
to  enclose  the  surfaces  of  the  stomach,  making  its  serous  coat.  They  come 
together  again  at  the  greater  curvature  and  hang  down  in  the  shape  of  a  large 
serous  sac  with  double  walls,  the  greater  omentum,  which  hangs  in  front  of  the 
small  intestine.) 

Note. — The  transverse  meso-colon  usually  becomes  adherent  to  the  greater 
omentum  (Fig.  112). 

THE  PANCREAS 

The  pancreas  (Figs.  109,  no)  is  a  racemose  gland,  behind  and 
below  the  stomach.  It  is  about  seven  inches  long  and  somewhat 
resembles  a  hammer  in  shape,  the  head  being  turned  to  the  right 
and  lying  within  the  curve  of  the  duodenum,  the  body  crossing  to 
the  left,  and  the  tail  reaching  the  spleen.  It  consists  of  lobules, 
each  with  its  duct;  these  unite  to  form  the  pancreatic  duct  which 
conveys  the  pancreatic  fluid  to  the  duodenum.  The  duct  opens 
(with  the  common  bile  duct)  into  the  duodenum  about  four  inches 
from  the  pylorus  (guarded  by  a  valve) . 

The  three  pancreatic  ferments  are  amylopsin,  trypsin  and 
steapsin  (for  starchy  proteid  and  fat)  (see  page  161). 

THE  LIVER 

The  liver  (Fig.  112)  is  the  largest  abdominal  organ,  and  the 
largest  gland  in  the  body.  Its  normal  weight  is  between  three 
and  four  pounds  (1300  to  1700  grams).  It  is  underneath  the  dia- 
phragm, in  the  right  upper  portion  of  the  abdomen,  the  thin  left 
lobe  extending  across  the  epigastric  region  above  the  stomach. 
Its  general  shape  is  that  of  a  wedge,  much  thicker  at  the  right  side 
than  the  left,  and  with  the  thin  edge  turned  forward.  The  upper 
surface  is  convex,  and  marked  off  by  a  ligament  into  two  lobes, 
right  and  left.  The  lower  surface  is  divided  by  five  fissures  into 
five  lobes.  The  largest  fissure  is  the  transverse,  the  porta  (or  gate) 
for  the  passage  of  vessels,1  nerves  and  ducts. 

1  Lymph  vessels  and  hepatic  artery.     Hepatic  veins  take  a  different  route. 


THE    LIVER 


149 


The  substance  of  the  interior  of  the  liver  is  composed  of  hepatic 
cells,  grouped  in  lobules,  with  a  multitude  of  blood-vessels,  lym- 
phatics and  nerves,  supported  by  connective  tissue. 


FIG.  112. — THE  ABDOMINAL  ORGANS. — (Gerrish,  after  Testut.) 
The  liver  is  turned  upward  to  show  the  inferior  surface  with  the  gall-bladder. 
The  vessels  entering  and  leaving  the  porta  are  also  seen,  the  lesser  omentum  having 
been  removed. 

An  hepatic  lobule  measures  only  about  a  millimeter  (£s  of  an  inch)  in 
width.  Between  its  cells  there  is  a  fine  network  of  hepatic  and  portal  blood- 
vessels, and  lymph  spaces;  also  bile  passages.  The  blood-vessels  empty  into 
hepatic  veins;  the  lymph  spaces  form  lymph  vessels,  and  the  bile  passages 
lead  to  small  bile  ducts  which  unite  and  reunite  to  form  the  hepatic  ducts. 


150  .      ANATOMY  AND   PHYSIOLOGY 

Five  ligaments  of  the  liver  hold  it  in  place  attaching  it  to  the 
diaphragm  and  abdominal  wall — the  round,  the  broad,  the  coronary, 
and  two  lateral. 

The  round  ligament  is  a  cord  (the  remains  of  the  umbilical  vein) 
inclosed  in  the  broad,  which,  with  the  lateral  and  coronary,  is  of 
peritoneum.  It  is  the  broad  ligament  which  connects  the  superior 
surface  of  the  liver  with  the  diaphragm  and  is  therefore  called  the 
suspensory  ligament.  It  also  marks  off  the  right  from  the  left 
lobe  on  that  surface.  The  principal  support  of  the  liver  is  by 
its  connection  with  the  diaphragm. 

The  liver  secretes  a  yellow  alkaline  fluid  called  bile  which  is 
conveyed  through  the  porta  by  two  ducts,  the  right  hepatic  and 
left  hepatic;  these  unite  to  form  one,  the  hepatic  duct  proper, 
which  is  soon  joined  by  the  cystic  duct  from  the  gall-bladder. 

The  gall-bladder  occupies  a  fissure  on  the  inferior  surface  of 
the  liver.  It  is  a  pear-shaped  sac  three  or  four  inches  long,  of 
fibrous  tissue  and  muscle  fibers  lined  with  mucous  membrane  and 
partially  covered  with  peritoneum.  It  contains  a  variable  quan- 
tity of  bile  (or  "gall")  in  reserve.  The  only  opening  of  the 
gall-bladder  is  for  the  cystic  duct,  which  joins  the  hepatic  to  form 
the  common  bile-duct,  or  ductus  communis  choledochus  (Figs. 
109,  112). 

Bile,  as  it  flows  from  the  gall-bladder,  is  a  thick  or  viscid 
yellow  fluid  having  sometimes  a  brown  tinge,  or  it  may  be  greenish. 
It  is  formed  as  a  thin  fluid  in  the  cells  of  the  hepatic  lobules, 
from  materials  brought  in  the  portal  vein  (which  enters  the  liver 
at  the  porta).  (See  page  148.) 

Its  characteristic  elements  are  bile  salts,  bile  pigment,  and 
cholesterol — a  substance  which  is  soluble  only  in  normal  bile. 
Any  of  these  may  be  found  in  gall-stones;  this  is  especially  true 
of  cholesterol. 

Bile  is  discharged  from  the  liver  by  the  right  and  left  hepatic 
ducts,  thence  into  the  hepatic  duct  proper,  and  the  common  bile 
duel  or  ductus  communis  choledochus,  as  already  stated. 

Note. — The  production  of  bile  is  continuous;  its  flow  into  the 
intestine  is  intermittent.  It  appears  in  the  duodenum  only  during 
the  process  of  digestion;  in  the  interval  it  is  stored  in  the  gall- 
bladder. 

Notes. — The  cystic  duct  is  about  i  1/2  inches  long;  the  hepatic 


THE    SPLEEN  151 

duct,  2  inches  long;  the  common  duct,  3  inches  long.  Just  before 
it  opens  into  the  duodenum,  the  common  duct  expands  into  a 
little  pouch  called  the  ampulla  of  Vater.  A  gall  stone  may  lodge 
in  this  place. 

Clinical  notes. — The  liver  is  pressed  downward  by  the  movement  (con- 
traction) of  the  diaphragm  in  inspiration,  and  can  then  be  felt  below  the 
costal  arch  in  front.  During  expiration  it  sJips  upward  with  the  rise  of  the 
diaphragm. 

Gall  stones  may  form  in  the  gall-bladder  or  in  any  of  the  ducts.  If  in  the 
gall-bladder  they  may  exist  for  a  long  time  without  causing  symptoms,  the 
bile  flowing  into  the  intestine  without  obstruction;  if  in  the  cystic  duct  the 
symptoms  are  also  deferred,  but  if  in  either  the  hepatic  duct  or  the  ductus 
communis,  obstruction  to  the  outflow  promptly  causes  jaundice  and  other 
disorders,  with  distention  of  the  gall-bladder.  Inflammation  of  the  gall- 
bladder is  Cholecystitis,  of  the  liver — hepatitis. 

The  mscidily  of  the  bile  is  increased  in  inflammation  of  the  gall-bladder 
and  often  clogs  the  ducts  to  the  point  of  obstruction,  as  in  jaundice. 

THE  SPLEEN 

Although  there  are  reasons  for  including  the  spleen  in  the  list  of  duct- 
less glands  it  is  decided  to  include  the  description  of  this  organ  in  the 
present  connection.  It  is  a  very  important  organ  with  a  remarkably  free 
blood  supply,  which  suggests  great  activity  for  some  purpose  or  purposes, 
and  the  only  direct  connection  of  the  spleen  with  any  other  organ  is  by 
blood-vessels  with  the  liver,  but  the  significance  of  this  is  a  matter  of  con- 
jecture at  the  present  time. 

The  spleen  (or  lien)  is  situated  at  the  left  of  the  stomach, 
directly  beneath  the  diaphragm  by  which  it  is  entirely  covered.  It 
is  oval  in  shape,  convex  on  the  lateral  surface  and  concave  on  the 
medial,  where  a  depression  called  the  hilus  is  seen  for  the  passage  of 
vessels  and  nerves  (Fig.  109). 

The  fibromuscular  capsule  which  forms  the  surface  of  the  spleen  sends 
numerous  septa  into  the  interior,  and  within  the  spaces  of  the  network  thus 
formed  the  splenic  pulp,  is  contained.  This  consists  of  blood  which  has 
escaped  from  the  open  terminals  of  numberless  capillaries,  of  lymphoid  cells 
and  broken  down  red  cells,  coloring  matter  and  particles  of  waste.  Small  col- 
lections of  lymphoid  cells  around  the  capillaries  may  be  seen  upon  section 
of  the  organ;  they  are  the  Malpighian  bodies  of  the  spleen;  their  function  is 
obscure. 

The  splenic  artery  is  the  largest  branch  of  the  celiac  axis  and 
the  consequent  large  blood  supply  gives  a  dark  red  color  to  the 


152  ANATOMY   AND   PHYSIOLOGY 

spleen.  The  peritoneal  covering  completely  surrounds  it,  except 
to  allow  vessels  and  nerves  to  pass  through  the  hilus. 

The  function  of  the  spleen  is  not  well  understood,  as  both 
animals  and  human  beings  have  been  known  to  live  in  health  after 
its  removal,  but  its  structure  and  the  study  of  the  blood  of  the 
splenic  artery  and  splenic  vein  reveal  the  following  facts: 

The  spleen  pulp  contains  a  vast  number  of  white  cells  (chiefly 
lymphocytes)  and  many  disintegrating  red  cells.  It  has  a  high 
percentage  of  iron,  especially  after  chronic  diseases.  The  blood  in 
the  vein  which  leaves  it  contains  many  more  white  cells  than  that 
in  the  artery  which  enters;  also — many  small  red  cells  are  present, 
some  of  which  are  still  nucleated  (newly  formed).  Two  enzymes 
are  found — one  a  uric-acid-forming  enzyme. 

From  these  observations  the  conclusions  suggested  are  that  the 
spleen  gives  birth  to  leucocytes;  that  it  stores  and  works  over  the 
iron  from  broken-down  tissues  (including  red  cells);  that  it  may 
assist  to  form  red  cells  and  that  it  forms  uric  acid  from  broken- 
down  protein  substances. 

Clinical  notes. — The  elasticity  of  the  capsule  allows  frequent  variations 
in  size,  which  in  health  are  normal;  it  is  always  larger  during  digestion  and 
smaller  in  fasting.  In  certain  diseased  conditions  it  is  much  increased  in 
size,  as  in  malaria;  and  notably  in  leukemia,  which  is  characterized  by  an 
enormous  increase  in  the  number  of  white  cells  in  the  blood,  as  well  as  in  the 
size  of  the  organ  itself.  The  significance  of  these  variations  in  size  is  not  yet 
explained. 


CHAPTER  IX 

PHYSIOLOGY  OF  THE  DIGESTIVE  ORGANS. 
FOODS,  DIGESTION,  ABSORPTION 

FOODS 

The  human  body  is  a  machine  constantly  in  motion;  therefore, 
its  cells  continually  use  up  their  force,  and  continually  need  renew- 
ing. The  material  for  this  renewal  is  supplied  by  the  food  which 
we  eat.  Substances  classed  as  foods  must  be  able  to  "repair  waste 
and  provide  the  raw  materials  for  growth.  All  substances  which 
have  this  power  are  foods.  .  .  .  Thus,  water  salts  and  oxygen 
are  true  foods"  (Mathews).  As  the  various  parts  of  the  body 
are  composed  of  quite  different  tissues,  so  the  food  is  of  a  mixed 
character. 

The  composition  of  the  tissues  includes  four  classes  of  food 
principles,  as  follows: 

1.  Proteins.  1 

2.  Carbohydrates  (sugars  and  starches).     \  organic. 

3.  Fats. 

4.  Mineral  salts  including  water.  inorganic. 
In  the  body  :— 

1.  Proteins  are  found  in  all  tissues,  but  most  abundantly  in — 
blood,  as  serum-albumin,  fibrinogen,  hemoglobin;  lymph,  as  serum- 
albumin;  muscles,  as  myosinogin;  milk,  as  caseinogen. 

2.  Carbohydrates  (sugars  and  starches)  are  found  principally 
in — blood,  as  dextrose;  liver  and  muscles,  as  glycogen;1  milk  as 
lactose. 

3.  Fats  are  found  principally  in — milk,  as  an  emulsion;  nerves, 
lymph,  blood  cells;  bones,  a?  marrow;  subcutaneous  fascia  and 
adipose  tissue  around  organs. 

4.  Mineral  salts  are  found  in  all  tissues  and  fluids  of  the  body; 

1  Glycogen  is  an  animal  starch  formed  within  the  body,  the  others  are  sugars. 
Dextrose,  grape  sugar  and  glucose  have  the  same  composition. 

153 


154  ANATOMY   AND    PHYSIOLOGY 

in — bones  and  teeth  especially,  as  lime  salts;  muscles,  nerves,  and 
blood,  as  potassium  salts;  all  tissues,  as  sodium  salts;  red  blood  cells, 
as  iron. 

In  the  food  :— 

1.  Proteins  exist  in — meats,  as  myosin  and  albumin;  eggs,  as 
albumin  in  the  white,  lecithin  in  the  yolk;  grains,  as  gluten; 
vegetables:  peas,  beans,  corn,  etc.,  as  vegetable  albumin. 

2.  Carbohydrates   (sugars   and   starches)    exist  in — fruits,   as 
dextrose  and  levulose;  milk,  as  lactose;  sugar  cane,  beets,  etc.,  as 
cane  sugar  and  saccharose;  vegetables:  peas,  beans,  potatoes,  etc., 
as  starch. 

3.  Fats  exist  in — milk,  as  an  emulsion;  corn,  oats  and  other 
grains;  eggs  (the  yolk)  and  all  animal  foods  in  varying  quantities. 

4.  Mineral  salts  exist  in — all  foods  (but  must  be  added  in  bulk) ; 
water,  the  most  important;  vegetable,  grains  and  protein  foods,  as 
phosphate  of  calcium ;  meats  and  all  animal  food,  as  iron ;  all  foods, 
as  sodium  chloride  or  common  salt. 

Proteins  must  be  supplied  to  all  tissues;  they  are  the  tissue 
builders. 

Carbohydrates  (or  sugars  and  starches)  are  utilized  by  liver 
and  muscle,  and  are  sources  of  heat  and  muscle  energy. 

Fats  are  needed  for  the  marrow  of  bones,  as  protective  cover- 
ings, and  to  fill  in  spaces  between  organs;  also  to  preserve  body 
heat  as  well  as  to  produce  it. 

Mineral  salts  are  necessary  to  life. 

Water  constitutes  nearly  three-fourths  of  the  body  weight, 
and  is  universally  present,  even  in  the  hardest  tissues,  as  the 
enamel  of  teeth.  Its  most  important  uses  are:  i.  To  hold  in 
solution  the  nutritive  principles  of  the  food,  that  they  may  be 
absorbed.  2.  To  sweep  away  waste  matters  to  organs  which 
can  secrete  them.  3.  To  aid  in  regulating  the  temperature  of 
the  body. 

Sodium  chloride  stands  next  in  importance  to  water.  It  is 
necessary  to  the  normal  activities  of  the  tissues.  It  contributes 
to  the  formation  of  hydrochloric  acid  for  gastric  juice. 

Phosphate  of  calcium  is  needed  by  bones  and  teeth;  it  is  the 
most  abundant  salt  in  the  body,  next  to  water. 

Calcium  is  indispensable  to  normal  blood. 

Iron  is  a  necessary  element  of  red  blood  cells,  in  hemoglobin. 


FOODS  155 

Elements  of  Organic  Food. — Sugar,  starch  and  fat  consist  of 
carbon,  hydrogen  and  oxygen  (CHO).  The  proteins  add  nitrogen 
(CHNO)  and  a  little  sulphur  (CHNOS).  (The  formula?  are  omit- 
ted, the  symbols  being  sufficient  for  our  purpose.)  These  ele- 
ments are  all  furnished  in  suitable  quantities  by  the  food  as 
described,  except  oxygen.  This  is  obtained  in  great  measure 
from  the  air  we  breathe  which  consists  of  nitrogen  and  oxygen. 
Nitrogen  simply  dilutes  the  oxygen,  being  itself  inactive  in  this 
combination. 

In  accordance  with  the  definition  of  food  given  at  the  beginning 
of  this  chapter,  we  regard  atmospheric  air  as  an  important  source 
of  food,  since  it  provides  the  essential  element  oxygen,  which 
constitutes  about  one  fifth  of  the  bulk  of  the  air  we  breathe  (see 
page  231).  It  passes  from  the  lungs  into  the  blood  and  is  carried 
by  the  red  cells  to  the  tissues  at  large. 

With  the  exception  of  oxygen  (which  is  introduced  through 
the  lungs),  food  enters  the  system  through  the  alimentary 
tract,  being  here  prepared  for  the  uses  for  which  it  is  designed, 
by  the  process  of  digestion. 

Different  articles  of  food  should  be  combined  in  such  ways  as 
to  secure  proper  adjustment  of  food  principles  to  body  needs. 

For  example:  with  meats,  vegetables  should  be  served  rather 
than  milk  or  eggs. 

Avoid  a  number  of  starchy  vegetables  in  the  same  meal.  For 
example:  to  potatoes,  or  rice,  or  hominy,  add  green  vegetables, as 
string-beans,  spinach,  celery,  etc. 

There  is  good  reason  for  adding  butter  to  bread  and  oil  to  salad, 
as  neither  flour  nor  green  things  contain  fat. 

Milk  is  well  combined  with  starchy  food,  having  within  itself 
both  proteins  and  fat.  Eggs  can  take  the  place  of  meat  to  a  large 
extent;  they  may  be  combined  with  milk. 

The  shell  or  husk  of  grain  contains  certain  mineral  salts  which 
are  about  our  only  source  of  silica  for  the  hair  and  teeth;  therefore 
— give  whole  grains  to  growing  children. 

Whole-wheat  flour,  and  ripe  beans  or  peas,  contain  protein  in  a 
vegetable  form;  ripe  corn  (cornmeat)  contains  more  fat  than  other 
cereals,  and  protein  as  well. 

All  vegetables  contain  a  varying  amount  of  fiber  which  is 
indigestible,  but  which  is  beneficial,  since  it  serves  to  prevent  the 


156  ANATOMY  AND   PHYSIOLOGY 

concentration  of  waste  matters  in  too  small  bulk  for  the  action  of 
the  large  intestine.  Three  reasons  for  cooking  food  are  as  follows: 

Cooked  starch  is  more  easily  digested  than  raw,  for  the  following 
reasons:  The  change  of  starch  into  sugar  requires  that  it  should 
first  be  hydrated,  that  is,  combined  with  water.  It  exists  in  gran- 
ules and  each  granule  of  starch  has  a  covering  of  cellulose  which  is, 
in  saliva,  indigestible.  In  the  process  of  cooking,  the  boiling 
water  penetrates  to  the  granule,  uniting  with  it  and  causing  it  to 
free  itself  from  the  envelope.  At  once  it  can  be  acted  upon  by 
ptyalin  if  in  the  mouth,  or  amylopsin  if  in  the  small  intestine. 
With  raw  starch,  hydration  goes  on  slowly  or  not  at  all.  Imper- 
fectly cooked  starch  is  unwholesome  for  the  same  reason. 

Vegetables  also  should  be  thoroughly  cooked  both  on  account 
of  the  starch  which  they  contain,  and  the  fibrous  material,  which 
needs  partial  disintegration  by  heat. 

Meats  are  more  easily  digested  if  cooked  long  enough  to  soften 
their  connective  tissue  fibers.  By  heat  these  are  converted  into 
a  gelatinous  substance  which  can  be  disposed  of  by  pepsin  and 
trypsin. 

Another  advantage  secured  by  the  cooking  of  food,  lies  in  the 
effect  of  the  flavors  thus  developed,  by  means  of  which  appetite 
is  encouraged  and  the  secretion  of  digestive  fluids  is  stimulated. 

Clinical  note. — The  "scraped  beef  sandwich, "  so  of  ten  ordered  for  patients, 
contains  the  substance  of  the  muscle  cell  alone,  which  has  been  scraped  away 
from  the  connective  tissue  fiber;  it  is  easily  digestible  because  it  may  at  once 
be  converted  into  peptone  without  the  necessity  for  first  digesting  the  tougher 
covering. 

DIGESTION 

Digestion  is  the  process  of  so  changing  the  food  in  the 
alimentary  canal  that  its  nutritive  parts  may  be  absorbed  into  the 
system. 

The  organs  described  in  Chapter  VIII  are  so  connected  and 
arranged  that  they  receive  and  act  in  consecutive  order  upon  the 
food,  causing  a  series  of  changes  which  result  in  separating  nutri- 
ment from  waste  and  preparing  it  for  absorption,  expelling  the  waste 
from  the  system. 

The  process  of  digestion  begins  in  the  mouth  and  continues 
throughout  the  small  intestine.  The  food  is  first  divided  into 


DIGESTION  157 

small  pieces  by  means  of  the  teeth.  This  is  mastication.  At  the 
same  time  it  is  mixed  with  saliva;  this  is  hydration  and  insalivation. 

By  the  act  of  swallowing,  the  softened  mass  is  passed  into  the 
pharynx  and  down  through  the  esophagus  to  the  stomach.  This 
is  deglutition.  (The  soft  palate  prevents  it  from  going  upward  to 
the  nose,  and  the  epiglottis  prevents  it  from  entering  the  larynx.) 

The  stomach  now  takes  charge.  The  mass  is  compressed  and 
moved  about  by  the  layers  of  the  muscular  coat  until  it  is  thor- 
oughly saturated  with  gastric  juice,  and  becomes  a  pale  yellowish 
fluid  called  chyme.  As  fast  as  this  is  accomplished,  the  pylorus, 
or  gate-keeper,  allows  it  to  go  through  into  the  duodenum,  where 
it  meets  the  intestinal  and  pancreatic  juices,  and  bile. 

Continuing  through  the  small  intestine  it  loses  in  increasing 
measure  its  fluid  and  nutritious  portions,  and  in  the  large  intes- 
tine it  is  still  further  reduced  to  waste  alone,  which  is  expelled 
from  the  body. 

Mechanical  Processes  of  Digestion 

The  passage  of  food  through  the  several  organs,  as  above 
outlined,  represents  the  sum  of  the  mechanical  processes  resulting 
from  the  peristaltic  action  of  the  muscles  of  the  tract,  which  are  al- 
ready described  as  consisting  of  layers  of  circular  and  longitudinal 
fibers  surrounding  the  tube  of  mucous  membrane.  In  addition 
to  these,  there  is  an  entirely  different  set — the  muscles  of  masti- 
cation, which  move  the  mandible  or  lower  jaw,  and  keep  the  food 
between  the  upper  and  lower  teeth.  Their  action  constitutes 
the  first  mechanical  process  of  digestion;  this  is  of  great  importance, 
because  only  when  the  food  is  in  small  fragments  (or  masticated) 
can  the  digestive  juices  have  access  to  the  whole  mass. 

Chemical  Processes  of  Digestion 

The  first  occurrence  which  follows  the  introduction  of  food  is 
an  increased  flow  of  blood  to  the  part  and  activity  of  the  secreting 
cells  as  the  food  arrives,  beginning  with  the  secretion  of  saliva. 
In  fact,  the  cells  may  begin  to  work  beforehand,  being  stimulated 
by  the  thought  of  food.  This  is  true  of  both  saliva  and  gastric 
juice. 

The  chemical  process  of  digestion  is  brought  about  by 
the  action  of  digestive  fluids  in  the  mouth,  stomach  and 


158  ANATOMY  AND   PHYSIOLOGY 

intestines — or  saliva,  gastric  juice,  and  intestinal  fluids;  it  is 
greatly  facilitated  by  the  presence  of  enzymes  in  the  fluids.  En- 
zymes are  organic  substances  which  are  the  result  of  cell  ac- 
tivity. Their  composition  is  undetermined;  we  know  them 
only  by  their  works.  The  characteristic  which  makes  them  valu- 
able is  their  power  to  stimulate  rapid  changes  in  certain  other 
substances  by  their  presence  alone,  while  they  themselves  remain 
unchanged.  In  this  way,  the  smallest  quantity  of  an  enzyme 
may  effect  changes  in  a  large  amount  of  material.  (See  p.  165.) 

In  the  mouth  the  mechanical  process  includes  mastication  and 
insalivation.  By  the  teeth  the  food  is  divided,  then  crushed  and 
ground;  at  the  same  time  it  is  softened  by  saliva.  The  parotid 
saliva  does  most  of  this,  being  the  most  abundant;  it  is  poured 
into  the  mouth  just  outside  the  upper  second  molar  and  thus  it 
mixes  at  once  with  the  mass  as  it  is  crushed  and  ground.  Sub- 
maxillary  and  sublingual  saliva  contain  much  more  mucin  and 
lubricate  as  well  as  soften  the  food.  The  saliva  also  dissolves 
the  sapid  substances,  in  order  that  the  nerves  of  taste  in  the  tongue 
may  appreciate  them.  One  can  neither  taste  nor  swallow  a  per- 
fectly dry  substance. 

In  the  mouth  the  chemical  process  is  the  conversion  of  starch 
into  sugar.  The  digestive  fluid  is  saliva;  the  two  enzymes  are 
ptyalin  (salivary  diastase)  and  maltase.  Ptyalin  does  most  of  the 
work — changing  the  starch  molecule  first  into  dextrin  and  then 
into  maltose  (and  a  little  dextrose) .  Not  all  the  starch  taken  at 
one  time  is  digested  in  the  mouth  for  the  reason  that  it  leaves 
the  mouth  too  soon.  (If  it  is  retained  in  the  mouth  for  some 
time,  especially  if  mastication  be  continued,  the  presence  of  the 
sugar  thus  formed  will  be  evident  to  the  taste.) 

The  digestion  of  starch  requires  an  alkaline  medium;  ptyalin 
cannot  act  in  acid  fluids. 

Saliva  is  alkaline. 

Being  masticated,  insalivated  and  hydrolyzed  (see  p.  166),  the 
food  is  now  prepared  for  deglutition  or  swallowing,  by  which  it  is 
passed  through  the  pharynx  and  esophagus  into  the  stomach. 
The  tongue  presses  against  the  hard  palate,  thus  giving  the  bolus 
(as  the  prepared  mass  is  called)  an  impulse  toward  the  isthmus 
of  the  fauces;  as  it  passes  through  this  space  the  upper  pharyngeal 
constrictor  muscle  grasps  it  and  passes  it  on — then  the  middle  and 


GASTRIC  DIGESTION  159 

the  lower  constrictors  in  turn — and  it  enters  the  esophagus. 
(Meanwhile  the  soft  palate  has  prevented  it  from  going  upward 
and  the  epiglottis  from  entering  the  larynx.) 

The  muscles  of  the  pharynx  and  upper  esophagus,  although  striped, 
are  not  absolutely  under  the  control  of  the  will;  we  may  or  may  not 
choose  to  swallow,  but  once  begun  the  act  completes  itself,  being  beyond  our 
power  to  interrupt. 

In  the  lower  portion  of  the  esophagus  (about  one-third)  the 
muscles  are  of  the  unstriped  variety  (this  is  the  first  appearance 
of  unstriped  muscle  in  the  alimentary  tract,  from  this  part  on  it 
has  no  other  kind) .  The  normal  movements  of  unstriped  muscle 
are  exactly  suited  to  the  requirements  of  the  digestive  process: 
they  are  deliberate  and  slow  instead  of  forcible  and  sudden,  in 
consequence  of  which  they  accomplish  not  only  the  passage  but 
the  softening  of  the  food  by  the  admixture  of  mucus  and  water, 
thus  facilitating  the  contact  of  the  digestive  fluid  with  the  whole 
mass.  Through  the  cardiac  sphincter  of  the  esophagus  it  enters 
the  stomach.  It  is  first  swept  to  the  fundus,  which  serves  as  a 
storehouse  while  successive  portions  of  the  food  are  acted  upon. 
In  the  stomach  the  mechanical  process  consists  in  the  action  of 
the  muscle  coats,  which  move  the  food  about  that  it  may  be 
still  more  softened  and  thoroughly  mixed  with  gastric  juice.  The 
contractions  of  the  muscles  of  the  stomach  go  on  in  a  wave-like 
manner  toward  the  pylorus,  alternately  constricting  and  relaxing 
the  walls  of  the  cavity. 

In  the  stomach  the  chemical  process  consists  in  conversion  of 
proteid  foods  into  peptones  and  amino-acids.  The  digestive 
fluid  is  gastric  juice.  The  enzymes  are  pepsin  and  rennin.  These 
act  upon  proteins  after  they  have  been  acidulated,  and  finally 
reduce  them  to  peptones.  (Some  protein  food  may  be  absorbed 
as  peptone  but  the  greater  part  is  reduced  to  still  simpler  forms, 
as  amino-acids,  etc.) 

Pepsin  cannot  act  in  alkaline  fluids;  gastric  juice  is  acid  (hydro- 
chloric acid  is  essential). 

In  the  digestion  of  meats,  the  acid  softens  the  connective  tissue 
fibers  (which  are  already  partially  gelatinized  by  cooking)  and 
thus  prepares  them  for  the  action  of  the  pepsin.  Eggs  are  digested 
in  the  same  manner  but  more  easily,  having  so  little  connective 
tissue. 


160  ANATOMY  AND   PHYSIOLOGY 

Milk  is  first  acted  upon  by  rennin  which  sets  free  the  albumin 
contained  and  brings  out  the  casein  from  the  caseinogen,  in  the 
form  of  a  soft  coagulum  or  curd.  Pepsin  then  transforms  both 
albumin  and  curd  into  peptone. 

Clinical  Note. — The  curdled  milk  which  a  healthy  baby  regurgitates  is  a 
normal  substance;  the  rennin  has  acted  and  it  only  needs  the  pepsin  to  com- 
plete its  digestion. 

The  protein  of  vegetables  is  digested  in  the  stomach  after  the 
cellulose  fibers  are  softened  by  the  acid.  Starch  may  undergo 
some  slight  degree  of  change  in  the  stomach  by  the  action  of 
the  saliva  which  was  mixed  with  it  in  the  mouth,  theptyalin  re- 
maining active  until  the  food  becomes  acidified. 

Fats  are  freed  from  their  connective  tissue  envelopes  and  float 
as  little  globules;  they  are  not  digested  here  (to  any  great  extent — 
this  is  still  uncertain) . 

Note. — The  mineral  salts  do  not  require  digestion.  They  are  already 
dissolved  in  the  water  for  the  purpose  of  entering  into  combinations  in  the 
tissues.  The  same  is  true  of  grape  sugar  (dextrose) . 

When  any  portion  of  the  stomach  contents  is  sufficiently  pre- 
pared by  gastric  digestion,  the  pyloric  sphincter  relaxes  and  the 
rather  thick  yellowish  fluid  called  chyme  passes  through  it  into  the 
duodenum  and  thence  into  the  jejunum  and  ileum. 

Chyme  contains  partially  digested  starch  and  proteins,  as  well 
as  sugars,  peptones,  fats,  water  and  mineral  salts,  gastric  juice 
and  some  mucus. 

The  acidity  of  the  chyme  when  it  reaches  the  pylorus  causes  the  con- 
traction of  certain  muscles  of  the  stomach  which  open  the  sphincter  and  allow 
the  flow  of  chyme  into  the  duodenum,  and  thence  into  the  ileum. 

In  the  intestine  the  mechanical  process  is  a  continuation  of  the 
peristaltic  movement  of  the  stomach.  The  circular  fibers,  by  fre- 
quent constrictions  of  the  tube,  divide  the  mass  and  force  it  along, 
at  the  same  time  preventing  a  too  rapid  passage.  The  longitudi- 
nal fibers  assist,  by  a  series  of  wave-like  contractions. 

The  chemical  process  consists  in  the  further  digestion  of  pro- 
teins, sugars  and  starch;  also  the  digestion  of  fats. 

The  intestinal  fluid  is  a  mixture  of  intestinal  juice,  pancre- 
atic juice  and  bile,  therefore  it  contains  several  ferments  or 
enzymes.  It  is  most  active  in  the  duodenum. 


INTESTINAL   DIGESTION  l6l 

Intestinal  juice  (succus  entericus)  completes  the  digestion  of 
proteins  and  sugar,  also  of  starch.  It  is  an  alkaline  fluid 
secreted  by  the  small  glands  of  the  intestine,  namely — the  glands 
of  Brunner  and  the  follicles  of  Lieberkuhn  or  intestinal  glands.  It 
contains  several  enzymes,  erepsin,  maltase,  invertase  and  others. 

By  erepsin  the  continuation  of  protein  digestion  is  carried  on, 
by  maltase  and  invertase  the  maltose  formed  in  the  mouth  from 
starch  is  converted  into  dextrose. 

Pancreatic  juice  is  an  alkaline  fluid  secreted  by  the  pancreas. 
Its  enzymes  are  several  in  number,  the  most  important  being 
trypsin,  amylopsin  and  steapsin.  Trypsin  completes  the  digestion 
of  proteins  already  begun  in  the  stomach,  carrying  it  still  further 
by  splitting  those  peptones  which  were  not  absorbed,  into  amino- 
acids.  (Trypsin  digestion  is  important.) 

Amylopsin  (pancreatic  diastase)  acts  like  ptyalin  (or  salivary 
diastase)  converting  starch  into  dextrose.  The  principal  digestion 
of  starch  is  accomplished  here. 

Steapsin  is  the  fat-splitting  enzyme.  Fats  are  probably 
freed  from  their  connective  tissue  envelopes  before  reaching  the 
intestine,  and  the  steapsin  splits  them  up  into  fatty  acids  and 
glycerine.  These  fatty  acids  combine  with  the  alkali  of  the 
intestinal  fluids  to  form  soaps,  which  in  solution  are  absorbable. 
(Also  soaps  can  emulsify  the  fats  which  continue  to  arrive,  that  is, 
divide  them  into  fine  particles  which  will  be  suspended  in  the 
alkaline  solution.) 

What  becomes  of  the  soaps?  Some  are  absorbed  as  such, 
some  form  an  emulsion  with  other  fats.  An  emulsion  was  long 
believed  to  be  the  only  form  in  which  fat  was  absorbed,  and  this 
is  not  yet  disproven.  At  all  events,  fat  still  appears  as  a  white 
emulsion  called  chyle  in  the  absorbing  vessels  of  the  small  intestine. 

The  third  important  constituent  of  intestinal  fluid  is  bile. 
This  is  an  alkaline  fluid  which  enters  the  duodenum  with  the 
pancreatic  juice  by  the  opening  at  the  bile  papilla. 

When  the  chyme  enters  the  duodenum,  the  acid  which  it  contains  causes 
the  opening  of  the  valve  of  the  common  duct,  and  the  bile  flows  into  the 
duodenum.  As  soon  as  the  chyme  is  made  alkaline  (by  bile  and  intestinal 
fluid)  the  valve  closes  not  to  be  again  opened  until  another  portion  of  acid 
chyme  is  received  from  the  stomach. 

The  bile  contains  no  digestive  enzymes, 
ii 


1 62  ANATOMY   AND    PHYSIOLOGY 

What,  then,  are  the  uses  of  the  bile  which  is  poured  into  the  in- 
testine with  the  pancreatic  juice? 

First,  it  is  alkaline  in  reaction — the  intestinal  enzymes  act  in 
an  alkaline  medium.  Second,  it  holds  the  soaps  in  solution, 
favoring  their  absorption.  Third,  it  assists  the  fat-splitting  func- 
tion of  steapsin  and  dissolves  fatty  acids  so  that  they  may  be 
absorbed.  Fourth,  it  accelerates  the  digestion  of  fats.  Fifth,  it 
delays  putrefaction  in  the  intestines,  probably — in  part — by  assist- 
ing peristalsis,  and  thus  preventing  stagnation  of  the  whole 
contents. 

Clinical  note. — Experiment  and  observation  prove  that  the  presence 
of  bile  is  necessary  to  nutrition.  Without  it  a  person  may  eat  large  quanti- 
ties of  food  and  still  lose  weight. 

The  work  of  digestion  is  continued  in  the  jejunum,  and  to  a 
lesser  degree  in  the  ileum.  By  the  absorption  of  digested  food, 
the  intestinal  contents  are  diminished  in  quantity  and  changed 
in  character,  containing  less  water  and  approaching  a  firmer 
consistency. 

After  passing  through  the  jejunum  and  ileum  into  the  large 
intestine,  some  digestion  may  still  go  on  by  the  action  of  the  in- 
testinal juice  which  was  incorporated  with  the  mass,  but  the 
major  portion  of  the  contents  of  the  colon  consists  of  undigested 
remnants  and  waste. 

From  the  foregoing  we  gather  the  following  summary: 

Proteins  are  digested  in  the  stomach  and  intestine.  The 
enzymes  are  pepsin  and  rennin,  trypsin,  and  erepsin.  Products 
of  protein  digestion,  peptones  and  amino-acids. 

Starches  are  digested  in  the  mouth  and  the  intestine.  En- 
zymes— ptyalin  in  the  mouth,  and  amylopsin  in  the  intestine. 
Product,  dextrose. 

Sugars  are  digested  in  the  mouth  and  intestine.  Enzymes — 
maltase  in  the  mouth,  and  maltase  and  imertase  in  the  intestine. 
Final  product,  dextrose.  Dextrose  (glucose,  grape  sugar)  and 
levulose  taken  with  the  food,  do  not  require  to  be  changed;  they 
are  already  soluble  and  absorbable. 

Fats  are  freed  from  their  connective  tissue  in  the  stomach, 
and  split  or  emulsified  in  the  intestine.  Products,  glycerine  and 
fatty  acids,  fat-emulsion. 


STIMULI   OF   DIGESTIVE    GLANDS  163 

Vegetables  are  digested  in  the  stomach  so  far  as  proteins  are 
concerned,  their  connective  tissue  having  been  previously  softened. 
Their  starch  and  sugar  content,  and  their  oils — as  above. 

The  best  temperature  for  digestion  is  the  normal  temperature 
of  the  interior  of  the  body,  or  about  100°  Fahrenheit. 

Clinical  note. — The  reason  for  abstaining  from  ice-water  during  digestion 

is  that  the  various  ferments  cannot  do  their  work  in  a  temperature  of  much  less 

than  100°  F.     (If  people  will  eat  ice-cream  after  dinner  they  should  take  it 

slowly,  that  the  whole  process  of  digestion  be  not  too  long  delayed  by  the 

•  necessity  of  waiting  for  the  temperature  to  rise  again  to  ioo°.) 

Warm  foods  make  less  of  a  demand  upon  the  vitality  of  the  body  than 
cold  ones. 

The  activity  of  the  digestive  glands  (like  that  of  all  others)  is 
called  forth  by  a  stimulus  of  some  sort  conveyed  to  the  gland  cells 
by  sympathetic  nerves. 

In  the  case  of  the  salivary  glands  this  stimulus  is  aroused 
by  several  things — first,  by  the  presence  of  food  in  the  mouth; 
second,  by  the  introduction  of  substances  which  have  an  agree- 
able flavor  or  odor;  third,  by  movements  of  the  muscles  of  mas- 
tication; fourth,  by  the  sensation  of  nausea;  fifth,  by  the  thought 
of  food  (which  is  a  psychic  stimulus).  The  salivary  secretion  is 
diminished  in  fevers  and  wasting  diseases,  also  by  certain  psychic 
impressions — as  fear,  anger,  anxiety,  and  the  like.  Everyone 
knows  the  dry  mouth  of  strong  emotion,  especially  if  associated 
with  apprehension. 

The  gastric  glands  respond  in  a  similar  manner;  the  presence  of 
food  in  the  stomach  causes  a  strong  flow,  flavors  and  odors  assist. 
Small  amounts  of  bitter  flavors  in  food  increase  it,  aromatic 
substances  have  the  same  effect. 

Clinical  note. — These  do  not  act  at  once;  therefore  aromatic  or  strongly 
flavored  medicines  should  be  given  a  quarter  of  an  hour  or  more  before  meals 
in  order  to  ensure  the  best  result. 

Water  increases  the  flow.  The  habit  of  taking  water  before 
meals  is  a  good  one,  but  if  taken  immediately  before  the  quantity 
should  be  small.  Alcohol,  like  the  bitters,  also  stimulates  the 
flow  of  gastric  juice. 

The  thought  of  food  causes  the  psychic  flow.  Strong  desire 
for  food,  or  appetite,  causes  a  psychic  flow  of  very  active  juice  within 


1 64  ANATOMY   AND   PHYSIOLOGY 

four  and   one-half   minutes.     The   thought  of   distasteful  food 
inhibits  the  flow  of  gastric  juice,  as  do  nauseous  flavors  and  odors. 

Clinical  note. — The  sense  of  distaste  diminishes  the  flow  of  gastric  juice, 
therefore  it  would  seem  wise  to  avoid  forcing  a  patient  to  take  more  than 
the  minimum  necessary  quantity  of  food  while  the  distaste  is  marked. 

Pepsin  is  sensitive  to  alkalies.  Alkalies  and  malts  may  favor 
a  flow  of  gastric  juice,  but  if  given  during  digestion,  they  destroy 
the  pepsin. 

Proteins  always  soften  when  treated  with  water,  and  become 
transparent  before  they  can  be  dissolved;  salty  foods  do  not  easily 
soften — they  are  not  easily  digested.  This  is  the  reason  why  it 
is  well  to  precede  the  cooking  of  dry  and  salty  foods  by  soaking 
in  water. 

The  presence  of  ordinary  fat  delays  digestion  in  the  stomach, 
although  a  very  finely  divided  fat,  as  in  cream  or  the  yolk  of 
egg,  may  be  there  partially  digested  by  a  ferment  called  gastric 
steapsin. 

An  accumulation  of  stomach  contents  is  embarrassing  to  the 
gastric  juice,  hence  the  advisability  of  deliberation  when  taking 
one's  meals. 

Note. — Hemoglobin  is  split  by  pepsin  into  hematin  and  a  globin.  The 
hematin  gives  the  dark  color  to  the  blood  which  is  vomited  after  gas- 
tric hemorrhage,  and  also  to  that  which  appears  in  f eces  after  intestinal 
hemorrhage.  (Hemoglobin  is  contained  in  the  red  cells  of  the  blood.) 

The  passage  of  food  through  the  intestine  is  normally  slow,  and 
thus  it  is  fully  exposed  to  the  surfaces  of  the  circular  folds  of  the 
mucous  membrane.  By  the  absorption  of  digested  food  the  intes- 
tinal contents  are  diminished  in  quantity  and  changed  in  character, 
containing  less  water  and  approaching  a  firmer  consistency.  After 
passing  through  the  ileo-colic  sphincter  into  the  large  intestine 
there  is  little  but  waste  remaining,  undigested  food  forming  the 
major  portion.  This  collection  of  waste,  liquids,  coloring  matter 
and  undigested  food  is  called  f  eces.  The  coloring  matter  is  derived 
partly  from  bile,  partly  from  food.  (It  may  be  modified  by  drugs ; 
for  example,  iron  and  bismuth  give  a  black  color  to  the  feces.) 
(The  odor  is  due  to  sulphuretted  hydrogen  and  to  skatol — it  also  is 
modified  by  food.)  The  consistency  depends  upon  the  amounts  of 
water  and  mucus,  approaching  a  liquid  form  when  the  intestinal 


DIGESTIVE    ENZYMES  165 

contents  are  hurried  through  the  tube  before  absorption  can  take 
place. 

Defecation  is  the  act  of  expelling  the  feces.  The  bowel  muscles 
contract  and  the  sphincter  ani  relaxes;  the  abdominal  muscles 
assist  by  compressing  the  organs  from  above.  The  dietary  which 
contains  the  largest  proportion  of  waste  material  will  leave  the 
greatest  quantity  of  feces  and  lead  to  more  frequent  defecation 
than  one  which  is  made  up  of  digestible  substances  only.  The 
peristaltic  action  of  the  bowel  is  made  more  effective  by  the  pres- 
ence of  a  reasonable  amount  of  matter  to  be  acted  upon. 

Clinical  notes. — Diarrhea  is  the  passing  of  frequent  loose  or  watery  stools. 
It  occurs  when  the  contents  of  the  small  intestine  are  hurried  along  too 
rapidly  by  some  irritating  substance  which  causes  excessive  peristalsis  and 
a  leakage  of  the  watery  portion  of  the  blood. 

Constipation  is  caused  by  a  too  concentrated  diet  and  slow  peristalsis. 
Since  bile  is  a  natural  stimulant  to  the  muscles  of  the  bowel,  constipation  is 
often  associated  with  a  torpid  liver;  it  is  also  caused  by  lack  of  fluids  in  the 
bowel.  Therefore  this  is  one  reason  why  water  is  an  important  food. 

Origin  of  enzymes  of  the  digestive  fluids. — They  are  formed, 
usually,  within  the  glandular  cells  of  the  organs  which  secrete 
the  fluids.  Sometimes,  by  the  fusion  of  a  substance  derived  from 
the  cell  with  another  called  a  pro-enzyme  which  it  meets  in  the 
fluid. 

For  instance,  the  pancreas  secretes  two  enzymes — amylopsin  and  steapsin. 
It  also  secretes  trypsinogen,  a  pro-enzyme  which  unites  with  a  special  sub- 
stance in  the  intestine  to  form  the  enzyme  try p sin.  In  the  one  case  (that 
of  amylopsin  or  of  steapsin)  the  enzyme  leaves  the  cells  already  formed,  in 
the  other  (that  of  trypsin)  it  is  formed  outside  of  the  cells. 

As  each  digestive  organ  secretes  its  own  fluid,  so  each  fluid  con- 
tains its  special  enzymes  for  special  purposes.  For  instance,  the 
enzymes  or  ferments  of  saliva  cause  rapid  digestion  of  starches, 
but  not  of  eggs  or  meat.  Those  of  the  gastric  juice  assist  the 
digestion  of  eggs  or  meats,  but  not  of  starches. 

While  it  would  probably  be  possible  to  digest  the  foods  by  the 
use  of  chemical  substances  alone,  as  acids  or  alkalies,  the  process 
would  require  such  a  high  temperature  that  the  body  could  not 
endure  it,  and  it  would  be  so  slow  that  we  might  starve  while 
waiting.  The  presence  of  enzymes  not  only  accelerates  the  process 
of  digestion,  but  allows  it  to  go  on  at  the  body  temperature,  hence 
their  great  importance. 


1 66  ANATOMY  AND   PHYSIOLOGY 

The  nature  of  the  changes  which  the  food  must  undergo  is,  a  separation 
or  splitting  into  simpler  bodies.  Most  food  substances  are  complex  and 
insoluble.  The  object  of  digestion  is  to  convert  them  into  simple  and  soluble 
substances  which  can  be  absorbed.  In  order  to  accomplish  this,  they  must 
be  not  only  mixed  with  water,  which  is  a  mechanical  process,  but  combined 
with  it  or  hydrolysed  which  is  a  chemical  process.  The  digestive  enzymes 
belong  to  the  class  called  hydrolytic  enzymes  because  they  act  by  hydrolysis. 

Hydrolysis  means  decomposing  the  water  which  is  present  and  uniting  its 
elements,  H  and  O,  with  other  substances  (also  in  process  of  decomposition  or 
breaking  down  by  the  action  of  the  same  enzyme). 

According  to  Hammarsten,  no  glands  in  the  body  can  work 
so  rapidly,  can  produce  so  great  a  quantity  of  fluid  in  the  same 
time  as  the  salivary  glands,  not  even  the  kidneys.  Eight  to  four- 
teen times  the  weight  of  all  the  glands  together  may  be  produced 
within  one  hour. 

Saliva  has  the  power  of  splitting  sulphureted  hydrogen  from 
the  sulphur  oils  of  onions,  radishes,  etc. 

Clinical  note. — Ptyalin  exists  in  the  saliva  at  birth  but  does  not  become 
active  under  three  or  four  months  of  age. 

SUMMARY 

Digestion.- — Is  the  process  of  so  changing  the  food  that  it  may 
be  absorbed. 

Absorption.' — Is  the  process  of  taking  up  certain  substances 
and  conveying  them  to,  the  blood. 

Circulation.' — Is  the  process  of  carrying  the  blood  and  other 
substances  to  every  part  of  the  body. 

Assimilation.' — Is  the  process  which  goes  on  in  the  tissue  cells 
whereby  they  make  use  of  the  food  which  is  conveyed  to  them. 

We  have  now  to  study  the  organs  which  distribute  the  products 
of  digestion,  and  the  composition  of  the  food-bearing  fluids — 
blood  and  lymph.  Assimilation  is  nature's  own  secret,  not  yet 
revealed  to  the  mind  of  man.  This  is  a  phase  of  metabolism. 

ABSORPTION  OF  FOOD 

Accompanying  the  digestion  of  food  the  absorption  of  nutritive 
principles  takes  place. 

It  is  quite  possible  that  some  portion  of  the  sugars  is  taken  up 
by  blood-vessels  of  the  stomach,  and  it  is  probable  that  more  or  less 


ABSORPTION   OF   FOOD 


167 


of  the  water  and  dissolved  salts  are  here  absorbed,  but  most  of  the 
stomach  contents  pass  through  the  pylorus  as  chyme  and  are  re- 
ceived by  the  duodenum  to  be  acted  upon  by  intestinal  fluids  and 
prepared  for  absorption.  The  mill  (Fig.  113)  are  the  absorbents 
which  perform  this  function  in  the  intestine.  The  epithelial  cells 
with  which  they  are  covered  take  up  and  transmit  the  new  sub- 


FIG.  113. — SECTION  OF  INJECTED  SMALL  INTESTINE  OF  CAT.  a.  b.  Mucosa. 
g.  Villi.  i.  Their  absorbent  vessels,  h.  Simple  follicles,  c.  Muscularis  mucosae. 
j.  Submucosa.  g,  6.  Circular  and  longitudinal  layers  of  muscle.  /.  Fibrous  coat. 
All  the  dark  lines  represent  blood-vessels  filled  with  the  injection  mass. — (Pier sol.} 

stances  into  lymph  spaces  within  the  villus,  from  which  they  go 
either  into  the  blood-vessels  or  lymph  capillaries  which  the  villus 
contains. 


Water  and  mineral  salts  (dissolved  in  the  water). — These  must  pass  into 
the  blood  capillaries,  thence  into  veins,  and  through  them  to  the  portal  vein 
(page  167).  By  this  they  are  taken  to  the  liver. 

Sugars  pass  by  the  same  route,  namely,  blood  capillaries  and  veins  to 
the  liver  from  the  intestine. 


1 68  ANATOMY  AND   PHYSIOLOGY 

Peptones  and  their  products,  amino-acids,  also  find  their  way  in  the  same 
manner  to  the  portal  blood  and  the  liver,  from  the  intestine. 

Thus  it  appears  that  all  proteins,  sugars,  water  and  salts  pass 
through  the  liver.  There,  water  and  salts  are  used  for  various 
combinations;  sugars  are  converted  into  glycogen  to  a  great  extent 
and  stored  for  future  use;  and  proteins  furnish  tissue  food  and 
materials  for  bile. 

Glycogen. — This  product  of  the  action  of  liver  cells  upon  carbohydrates  is 
stored  in  the  liver.  When  needed  it  is  returned  to  the  blood  (as  sugar  again) 
and  distributed  to  the  tissues,  notably  to  the  muscles.  Being  readily  oxidized 
it  favors  the  rapid  changes  in  muscles  which  result  in  motion.  Therefore,  it 
follows  that  sugar  and  starch  are  sources  of  muscle  energy. 


Lacteal  s 
Blood  vessels 

%^w:; 


FIG.  114. — LOOP  OF  SMALL  INTESTINE  WITH  LACTEALS. — (Morris.) 

Urea. — This  is  another  substance  which  appears  as  a  result  of  the  activity 
of  the  liver  cell.  It  is  one  of  the  final  forms  of  waste  derived  from  the 
metabolism  of  protein  substances.  It  is  a  very  poisonous  waste  and  is  elim- 
inated from  the  blood  by  the  kidneys. 

Having  yielded  materials  for  these  functions,  the  remaining 
food  substances  are  carried  away  from  the  liver  by  hepatic  veins 
and  finally  into  the  general  circulation,  to  be  distributed  to  the 
tissues  of  the  body. 

There  remain  the  fats:  These,  being  transferred  by  the  epithe- 
lial cells  to  the  lymph-spaces,  take  the  other  route,  in  the  form  of 
an  emulsion  known  as  chyle.  They  pass  into  the  lymph  capillaries 


ABSORBENT  VESSELS 


169 


FIG.  115. — DIAGRAM  SHOWING  THE  ROUTES  BY  WHICH  THE  ABSORBED  FOODS 
REACH  THE  BLOOD  OF  THE  GENERAL  CIRCULATION  (G.  Bachman).  I.  i.,  Loop  of 
small  intestine;  int.v.,  intestinal  veins  converging  to  form  in  part,  p.  v.,  the  portal 
vein,  which  enters  the  liver  and  by  repeated  branchings  assists  in  the  formation  of 
the  hepatic  capillary  plexus;  h.  v.,  the  hepatic  veins  carrying  blood  from  the  liver 
and  discharging  it  into,  inf.  v.  c.,  the  inferior  vena  cava;  int.  L  v.,  the  intestinal 
lymph  vessels  converging  to  discharge  their  contents,  chyle,  into  rec.  c.  the  receptac- 
ulum  chyli,  the  lower  expanded  part  of  the  thoracic  duct;  th.  d.,  the  thoracic  duct 
discharging  lymph  and  chyle  into  the  blood  at  the  junction  of  the  internal  jugular 
and  subclavian  veins;  sup.  v.  c.,  the  superior  vena  cava. — (From  Brubaker's  Text- 
book of  Physiology.') 


170  ANATOMY   AND    PHYSIOLOGY 

of  the  intestine  (so-called  lacteals),  which  open  into  the  lymph 
vessels  in  the  submucous  coat.  By  these  vessels  the  chyle  finally 
reaches  the  thoracic  duct  and  is  carried  to  the  blood,  to  be  distrib- 
uted to  the  tissues  of  the  body  by  way  of  the  general  circulation. 

Osmosis 

The  forces  which  regulate  absorption  include  the  process  of 
osmosis,  which  has  been  described  as  the  passage  of  "  diffusion 
streams"  whereby  solutions  of  different  strengths  or  densities 
pass  through  animal  membranes.  This  does  not  explain  all  that 
happens;  it  is  recognized  that  certain  very  important  chemical 
processes  must  be  involved  in  the  cell  walls  of  the  intestines,  the 
nature  of  which  is  beyond  our  present  understanding.  We 
bid  farewell  to  peptones  and  amino-acids  in  the  intestinal  canal 
and  greet  albumins  and  fats  in  the  blood-vessels  which  leave  it; 
we  find  solutions  of  soaps  and  fatty  acids  on  the  outside  of  the 
villus — emulsified  fat  in  the  lymph  tube  within. 

The  same  forces  by  which  the  nutritive  fluids  were  absorbed 
into  the  vessels,  are  again  at  work  to  effect  their  transference 
from  the  vessels  to  the  tissues  of  the  body. 

In  the  tissues. — The  solution  of  nutritive  substances,  having 
been  carried  by  the  blood-vessels  to  the  minutest  channels  in  the 
body,  passes  into  the  tissue  spaces  as  lymph,  which  bathes  the  cells 
themselves,  so  that  they  may  receive  the  material  necessary  for 
their  action  and  upbuilding. 

Different  tissues  appropriate  their  different  foods,  and  each 
gives  back  the  products  of  its  own  activities  as  tissue  wastes, 
which  in  turn  enter  the  blood  to  be  carried  to  tissues  which  can 
make  another  use  of  them,  or  to  organs  which  can  dispose  of  them 
as  excretions. 

The  next  chapter  will  introduce  the  study  of  the  blood,  heart 
and  blood-vessels,  or  the  system  of  circulatory  organs  for  dis- 
tributing the  blood  throughout  the  body. 


CHAPTER  X 
THE  BLOOD  AND  CIRCULATORY  ORGANS 

THE  BLOOD 

The  blood  is  the  most  important  fluid  in  the  body.  It  not  only 
carries  food  to  every  part,  but  bears  waste  matters  to  those 
organs  which  can  dispose  of  them  in  the  form  of  excretions.  It 
consists  of  a  clear  yellowish  fluid  called  plasma  and  small  round 
cells  (invisible  to  the  naked  eye)  called  corpuscles  (little  bodies), 
which  float  in  the  plasma.  The  corpuscles  are  of  two  sorts,  red 
and  white. 


FIG.  1 1 6. — CORPUSCLES  OF  BLOOD,  AS  SEEN  UNDER  THE  MICROSCOPE. 
Four  white  ones  are  shown.     The  red  ones  have  a  tendency  to  form  rows. — (Funke 

and  Brubaker.) 

It  is  convenient  to  follow  the  usage  common  in  clinical  work  and  speak  of 
them  as  red  and  white  cells. 

Blood  has  a  characteristic  odor  which  varies  in  different  animals. 

The  temperature  of  the  blood  is  about  100°  F. 

The  reaction  is  alkaline. 

The  red  cells  (erythrocytes)  are  non-nucleated,  flexible  and 
elastic.  They  are  very  numerous,  numbering  4,000,000  to 
4,500,000  in  a  cubic  centimeter.  They  measure  about  ^3  of 
an  inch  in  diameter,  and  their  shape  has  been  usually  described 

171 


172  ANATOMY   AND   PHYSIOLOGY 

as  that  of  a  flattened  sphere  (Fig.   116).     (They  are  oxygen- 
carriers.) 

Note. — The  illustration  presents  the  appearance  under  the  microscope 
of  blood  which  has  been  removed  for  a  time  from  the  vessels  and  cooled. 
Careful  studies  under  other  conditions  indicate  that  the  living  cells  are 
slightly  bell-shaped.  In  the  early  stage  of  formation  they  contain  a  nucleus. 

The  red  cells  are  composed  largely  of  hemoglobin  held  in  a  net- 
work or  stroma  of  protoplasm.  This  itself  is  amber  colored,  but 
when  a  great  number  of  cells  are  together  as  in  a  drop  of  blood, 


FIG.  117. — WHITE  CORPUSCLES  PENETRATING  CAPILLARY  WALLS. — 
(Landois  and  Stirling.} 

it  gives  the  red  hue  to  the  fluid.  The  color  varies  with  the 
quantity  of  oxygen  in  the  cell,  from  bright  scarlet  with  much 
oxygen  to  bluish  red  with  little.  Hemoglobin  is  a  protein  substance 
whose  most  important  property  is  its  power  to  combine  with 
oxygen  forming  oxy-hemoglobin,  and  to  give  it  up.  It  contains 
a  minute  quantity  of  iron  in  combination  (hematin)  which  is  neces- 
sary to  life  processes. 

The  origin  of  the  red  cells  is  in  the  red  marrow  of  cancellous 
bone. 

The  white  cells  or  leucocytes  are  of  different  sizes  (the  average 
size,  about  ^00  of  an  inch  in  diameter).  They  move  more  slowly 
in  the  plasma  and  are  far  less  numerous,  numbering  only  about 
7500  in  a  cubic  centimeter. 

They  are  nucleated,  flexible  and  elastic.  Their  shape  is  spher- 
ical (often  irregular) ,  and  they  consist  of  a  transparent  material 
containing  one  or  several  nuclei  and  many  fine  granules  of  protein 
substances  of  several  kinds.  They  also  contain  glycogen  and 
enzymes. 


THE    LEUCOCYTES 


173 


The  white  cells  frequently  change  their  shapes  by  means  of 
ameboid  movements,  that  is,  like  the  ameba,  they  thrust  out  portions 
of  their  substance  and  draw  them  back.  They  can  send  out  little 
prolongations  and  draw  floating  particles  to  themselves,  or  they 
can  wrap  themselves  around  foreign  substances. 

They  possess  also  the  power  of  slipping  (squeezing)  through  the 
walls  of  capillary  vessels.  This  is  called  diapedesis  (Fig.  117). 

Of  the  several  varieties  of  leucocytes  the  percentage  of  polymorpho- 
nuclear  cells  (nuclei  of  many  shapes)  is  the  largest. 

The  polymorphonuclear  cells  (oftenest  called  polynuclear)  and 
the  lymphocytes  are  called  phagocytes,  because  they  destroy 
bacteria  by  absorbing  and  digesting  them.  This  process  is  called 
phagocytosis  (to  be  referred  to  later  on)  (pp.  214  and  220). 

The  origin  of  the  white  cells  is  from  two  sources :  the  lymphocytes 
originate  in  lymph  glands  and  other  lymphoid  tissues;  the  poly- 
nuclear  leucocytes  and  others  are  developed  from  cells  in  the  marrow 
of  long  bones.  A  third  form  of  colorless  cell  is  called  a  blood  plate 
or  platelet. 

The  platelets  are  very  small,  being  barely  one-half  the  size  of 
the  ordinary  cells.  They  are  similar  to  leucocytes;  their  origin 
is  not  understood,  but  they  take  an  important  part  in  the  coagu- 
lation of  blood. 

The  plasma  is  a  thin  watery  saline  fluid  in  which  the  corpuscles 
float.  It  contains  both  nutritive  and  waste  matters  in  solution, 
and  certain  elements  from  which  fibrin  is  derived,  also  enzymes 
(and  certain  extractives).  Fibrin  is  essential  to  the  production 
of  a  blood-clot,  without  which  hemorrhage  would  never  cease  of  its 
own  accord.  (Fibrin  and  corpuscles  removed — serum  remains.) 

The  substances  dissolved  in  the  watery  portion  of  the  plasma  are : 


Nutritive  (derived  from  food) . . 


Waste  products  (derived  from 
tissue  changes). 

Mineral  salts.     Chiefly  salts  of 


Proteins  (chiefly) 


Sugars 
Fats 

Extractives 

Sodium 

Potassium 

Calcium 


(  Serum-albumin 
Paraglobulin 
Fibrinogen 
Prothrombin  (or 
Thrombogen) 


Urea 

Uric  acid,  etc. 


174  ANATOMY  AND   PHYSIOLOGY 

The  serum-albumin  is  the  great  tissue  builder.  The  fibrinogen 
is  a  fibrin  maker  (paraglobulin  may  assist,  its  use  is  not  fully 
known). 

Sugars  and  fats  are  tissue  foods  and  sources  of  heat. 

Mineral  salts  preserve  the  necessary  alkalinity  of  the  blood  and 
assist  in  the  formation  of  certain  tissues  (as  bone).  Sodium 
chloride  (common  salt)  is  the  most  abundant  and  to  this  is  due  the 
salinity  of  the  blood.1  Salinity  is  an  exceedingly  important 
quality  of  plasma.  It  is  essential  to  the  interchange  of  fluids 
between  the  vessels  and  the  tissues  and  to  the  maintenance  of 
the  rhythmic  action  of  cardiac  muscle.  It  is  also  necessary  for 
the  preservation  of  blood  corpuscles.  Pure  water  invades  them 
(by  osmosis)  and  so  dilutes  them  that  they  swell  and  are  de- 
stroyed. The  salinity  of  plasma  is  the  same  as  that  of  the  cells, 
therefore  no  "diffusion  streams"  (or  osmosis)  can  occur  and  the 
cells  are  safe.  For  Coagulation  of  Blood  see  p.  217. 

THE   CIRCULATORY  ORGANS   OF  THE  BLOOD 

This  system  includes  the  heart  and  blood-vessels  (arteries, 
capillaries  and  veins).  They  are  the  organs  which  contain  the 
blood. 

The  heart  is  a  pump.  The  arteries  are  elastic  tubes  which  re- 
ceive the  blood  directly  from  the  heart.  The  capillaries  are  small 
vessels  into  which  the  arteries  lead,  and  the  veins  carry  the  blood 
from  the  capillaries  back  to  the  heart. 

Arteries. — Vessels  which  convey  the  blood  away  from  the  heart. 
They  are  flexible  tubes  whose  walls  consist  of  three  layers  or 
coats — external,  middle,  and  internal  (or  tunica  adventitia,  tunica 
media,  and  tunica  intima).  The  external  coat  is  composed  of 
fibrous  tissue  to  which  the  strength  and  toughness  of  the  vessel  is 
due;  the  middle  is  composed  of  elastic  tissue  and  unstriped  muscle 
fibers,  giving  to  arteries  their  yielding  and  contractile  chracter; 
the  internal  is  thin  and  smooth  and  is  a  continuation  of  the  lining 
of  the  heart.  Arteries  of  medium  size  have  most  muscle  tissue, 
while  the  larger  ones  have  most  elastic  tissue.  It  is  owing  to 
their  elasticity  that  arteries  remain  open  when  they  are  empty 
or  cut  across. 

1  A  "normal  saline  solution"  contains  salt  in  the  proportion  found  in  blood. 


CAPILLARIES  —  VEINS  175 

Note.  —  The  internal  coat  is  the  only  one  which  is  continuous  throughout 
the  entire  circulatory  system. 

Surgical  note.  —  When  a  ligature  is  tied  tightly  around  an  artery  the  middle 
coat  may  be  felt  to  break  down  under  the  cord,  while  the  external  one  remains 
whole,  owing  to  its  toughness. 

The  arteries  give  off  branches  which  divide  and  subdivide  until 
the  smallest  ones  can  be  seen  only  with  the  microscope  —  they  are 
called  arterioles.  The  arterioles  lead  to  the  vessels  which  are 
smallest  of  all  —  the  capillaries. 

Capillaries.  —  Vessels  which  receive  blood  from  the  arteries  and 
carry  it  to  the  veins.  They  exist  in  nearly  every  part  of  the  body, 
except  cartilages,  hair,  nails,  cuticle,  and  the  cornea  of  the  eye. 
Their  walls  have  only  the  internal  coat,  a  single  layer  of  cells  — 
endothelium.  It  is  through  this  thin  wall  that  the  work  of 
exchange  is  performed  between  the  blood  and  the  various  tissues  of 
the  body,  nutritive  material  being  taken  from  the  blood  and  certain 
waste  substances  being  returned  to  it.  To  provide  vessels  for  this 
exchange  is  the  function  of  the  capillaries.  They  are  most  numer- 
ous where  most  work  is  to  be  done,  viz.,  in  the  lungs,  skin,  mucous 
membranes,  liver,  kidneys  and  glands. 


Their  average  diameter  is  WFIO  of  an  inch  —  just  enough  to  permit  the  easy 
passage  of  the  corpuscles.  They  are  uniform  in  size,  neither  increasing  nor 
diminishing  in  caliber. 

Veins.  —  The  vessels  which  gather  the  blood  from  the  capil- 
laries and  carry  it  to  the  heart;  they  are  formed  by  the  uniting  of 
capillaries. 

They  are  at  first  very  small  (called  venules  or  venous  radicles]  but  constantly 
grow  larger  by  uniting  with  each  other,  although  they  often  branch  and 
reunite. 

Veins,  like  arteries,  have  three  coats,  but  their  middle  coat  is 
neither  so  elastic  nor  so  muscular,  so  that  they  are  softer,  and  when 
empty  or  cut,  they  collapse.  The  inner  coat  of  the  veins  presents, 
at  intervals,  semilunar  folds,  making  pockets  called  valves,  which 
allow  the  blood  to  flow  toward  the  heart,  but  prevent  it  from  setting 
backward  freely.  If  the  veins  are  very  well  rilled  the  location  of 
the  valves  may  be  recognized  by  an  appearance  of  puffing  out  at 


170  ANATOMY   AND    PHYSIOLOGY 

those  points  where  they  exist  (Fig.  118),  as  the  blood  fills  the 
pockets  from  above. 

Blood-vessels  possess  nerves  (the  vaso-motors)  which,  by  con- 
trolling the  muscular  coats,  regulate  the  amount  of  blood  flowing 
through  them  at  a  given  time  to  the  structures  which  they 

supply.     (An  organ  at  work  needs  more  blood 

than  an  organ  at  rest.) 

They  also  possess  tiny  blood-vessels  in  their  walls, 
the  vasa  vasorum. 

All  blood-vessels  have  sheaths  of  connective 
tissue.  In  the  case  of  the  larger  ones  these  are 
quite  strong  and  sometimes  inclose  a  vein,  an 
artery,  and  a  nerve  together  for  protection. 

THE  HEART 

The  heart  is  a  hollow  muscular  organ  through 
which  the  blood  passes,  placed  behind  the  ster- 
num and  just  above  the  central  tendon  of  the 
FlG    Iig  _A  diaphragm.     Its    average    size    is    about    five 

VEIN  LAID  OPEN  TO  inches  long  by  three  and  one-half  wide,  and  two 
SHOW  VALVES.  ,  ,     ,r    ,.  , 

and  one-half  thick. 

Note. — The  muscle  tissue  of  the  heart  te  called  the  myocardium. 

It  is  shaped  like  a  cone,  about  five  inches  long  and  three  and 
one-half  inches  wide,  with  the  base  turned  upward  toward  the  right 
shoulder  and  the  apex  pointing  downward  toward  the  left  side. 
It  is  composed  of  several  layers  of  muscle  fibers  which  are  peculiar, 
being  involuntary  and  at  the  same  time  striped. 

The  cavity  of  the  heart  is  divided  by  a  septum  into  right  and 
left  portions,  and  as  it  lies  in  the  body  the  right  heart  is  nearly  in 
front  of  the  left.  Each  side  consists  of  two  chambers,  an  auricle 
(atrium)  and  a  ventricle  (ventriculum)  (Fig.  120). 

The  auricles  receive  blood  and  pass  it  into  the  ventricles. 
Their  walls  are  thin  and  flabby.  The  right  auricle,  or  atrium, 
presents  two  large  openings  for  the  entrance  of  veins,  and  one  for 
communication  with  the  right  ventricle.  The  veins  are  the 
superior  vena  cava  from  the  head  and  upper  extremities;  the  inferior 


THE  VENTRICLES 


177 


vena  cava  from  the  trunk  and  lower  extremities.  It  also  has  a 
transverse  fold  on  the  posterior  wall  called  the  Eustachian  valve 
or  valve  of  the  inferior  vena  cava,  and  a  round  depression  on  the 
septum  between  the  two  auricles  (atria),  called  the  oval  fossa  (fossa 
ovalis).  The  left  auricle  presents  two  large  openings  and  several 
small  ones  for  veins,  and  communicates  with  the  left  ventricle. 


Posterior  branch  of 
right  coronary  ar 
tery 

Auricular  appendage 
Right  coronary  artery 

Preventricular    branch 
Right  marginal  branch 


Posterior  interventicu- 
lar  branch  of  right 
coronary  artery 


r 

\M^< 

[RIGHT    ^f 

^VENTRICIL'E 


Transverse  branch   of 
right  coronary  artery 


Left  coronary  artery 


Anterior  interventricu- 
lar  branch    of  left 
coronary  artery 


Left  marginal  branch 


FIG.  119. — ANTERIOR  SURFACE  OF  HEART. — (Morris.) 
The  coronary  arteries  supply  the  substance  of  the  heart. 

The  ventricles  expel  blood  from  the  heart.  They  include  the 
apex  of  the  heart;  their  walls  are  thick  and  strong,  the  left  one 
being  the  thicker  and  larger  of  the  two.  Certain  muscle-fibers  in 
the  ventricles  pass  downward  to  wind  around  the  apex  of  the  heart 
and  then  turn  upward;  others  are  transverse,  still  others  oblique; 
the  arrangement  causing  the  heart  to  harden  in  contraction,  with  a 
twisting  motion  from  right  to  left  and  a  forcible  pressure  against 
the  chest  wall.  This  is  felt  in  the  fifth  interspace,  at  the  left  of  the 
sternum  and  is  called  the  cardiac  impulse. 

The  muscle  band  of  His  (auriculo-ventricular  bundle)  is  a  name 
given  to  a  bundle  of  muscle  fibers  which  connects  the  auricles  and 
ventricles;  the  contraction  impulse  is  believed  to  travel  from  auricle 
to  ventricle  by  these  fibers. 


12 


178  ANATOMY   AND   PHYSIOLOGY 

The  interior  of  the  ventricles  is  marked  with  a  number  of  ridges 
or  bands  of  muscle  fibers  (the  trabeculce  carnece),  and  certain  of 
these  are  attached  by  tendinous  cords  to  the  valves  of  the  heart. 
Each  ventricle  opens  into  a  large  artery,  which  conveys  the  blood 
away — the  pulmonary  artery  from  the  right  ventricle,  the  aorta 
from  the  left. 


3" 

FIG.  120. — INTERIOR  or  LEFT  HEART.     (Observe  the  difference  in  thickness  of 

the  walls  in  auricle  and  ventricle.) — (Allen  Thomson  in  Brubaker.) 
i,  L.  atrium  or  auricle;  2,  division  between  it  and  ventricle;  3,  wall  of  left  ventricle; 
4,_a  band  of  muscle  fibers  severed;  5,  other  muscle  bands;  6,  a  leaflet  of  mitral  valve, 
with  tendinous  cords;  7,  aorta  (a  large  artery)  laid  open  to  show  semilunar  valves;  8, 
pulmonary  artery  (semilunar  valves  closed) ;  9,  arch  of  aorta. 

Note. — In  the  new  nomenclature  the  name  "atrium,"  or  forechamber ,  is 
given  to  the  main  part  of  the  auricle,  and  the  word  auricle  applies  to  the 
auricular  appendage  alone. 

Endocardium. — The  lining  of  the  heart.  It  is  thin  and  firm, 
resembling  serous  membrane  in  appearance,  and  is  continuous 
with  the  lining  of  the  blood-vessels,  thus  making  a  perfectly 


CARDIAC  VALVES  179 

smooth  surface  of  endothelium  throughout,  for  the  current  of  blood 
in  heart  and  vessels. 

THE  VALVES  OF  THE  HEART 

The  valves  of  the  heart  are  formed  by  folds  of  endocardium 
strengthened  by  fibrous  tissue  and  attached  to  fibrous  rings  around 
certain  orifices  of  the  different  chambers — two  in  the  right  heart 
and  two  in  the  left.  The  opening  between  the  right  auricle  and 
ventricle,  or  tricuspid  orifice,  is  guarded  by  the  tricuspid  valve, 
which  is  composed  of  three  leaflets.  It  allows  the  blood  to  flow 
down  into  the  ventricle  but  prevents  it  from  flowing  back.  The 
opening  between  the  left  auricle  and  ventricle,  or  mitral  orifice,  is 
guarded  by  the  bicuspid  (or  mitral)  valve,  composed  of  two  leaflets, 


FIG.  121. — VALVES  OF  THE  HEART. 

i.  Right  auriculo-ventricular  orifice,  closed  by  the  tricuspid  valve.  2.  Fibrous 
ring.  3.  Left  auriculo-ventricular  orifice,  closed  by  the  mitral  valve.  4.  Fibrous 
ring.  5.  Aortic  orifice  and  valves.  6.  Pulmonic  orifice  and  valves.  7,  8,  9. 
Muscular  fibers  (auricles  removed). — (Bonamy  and  Beau.} 

allowing  the  blood  to  flow  down  into  the  ventricle  but  not  to 
return.  (Both  the  tricuspid  and  mitral  valves  are  connected  to 
certain  muscle  bands  of  the  ventricles  by  tendinous  cords  which 
control  the  motion  of  the  leaflets,  preventing  them  from  flying 
upward  too  far  when  the  ventricles  contract.)  (Fig.  120.) 

The  opening  from  the  right  ventricle  into  the  artery  which 
leaves  it  (pulmonary  artery) ,  is  guarded  by  three  semilunar  valves, 
which  are  half-moon  shaped  pockets  called  the  pulmonary  valves. 
Likewise  the  opening  from  the  left  ventricle  into  its  artery  (aorta) 
is  guarded  by  three  semilunar  valves  called  the  aortic  valves 
(Fig.  121). 


l8o  ANATOMY   AND   PHYSIOLOGY 

The  semilunar  valves  allow  the  blood  to  flow  in  one  direction 
only — that  is,  away  from  the  heart. 

FUNCTIONS  OP  THE  CHAMBERS  OF  THE  HEART 

The  auricles,  having  received  blood  from  the  veins  opening  into 
them  (the  right — blood  from  entire  body;  left — from  lungs  alone) 
gently  contract  together  to  send  it  down  into  the  ventricles; 
quickly  the  •  ventricles  contract,  forcibly  and  together,  expelling 
blood  into  the  two  large  arteries — the  pulmonary  carrying  it  to  the 
lungs,  the  aorta  to  all  parts  of  the  body.  This  process  is  the  systole 
of  the  heart;  it  occupies  about  eight-tenths  of  a  second,  perhaps  a 


FIG.  122.     (DIAGRAM.) 

The  right  auricle  receiving  blood  and  passing  it  through  tricuspid  valve  into  right 
ventricle,  which  is  dilated  (semilunar  valves  closed), — (Dalton  in  Brubaker.) 

trifle  more.  Then  comes  the  resting-time  when  the  heart  is  dilat- 
ing and  filling  again,  called  the  diastole  of  the  heart. 

One  systole  and  one  diastole  together  constitute  a  cycle  of 
the  heart. 

During  the  systole  of  the  auricles,  the  tricuspid  and  mitral 
valves  are  open  and  the  semilunar  valves  are  closed.  During 
systole  of  the  ventricles  the  tricuspid  and  mitral  valves  close,  and 
the  semilunar  valves  are  open  (Figs.  122,123).  See  Heart  Sounds 
(closure  of  valves) . 

The  thickness  of  the  ventricle  wall  is  explained  by  the  need  for 


THE   PULSE  l8l 

sending  blood  to  a  distance,  the  greater  thickness  of  the  left  being 
made  necessary  by  the  far  greater  work  required  of  it. 

The  activity  of  the  heart  is  unlike  that  of  any  other  organ  in  its 
periods  of  working  and  resting.  The  nerve-muscle  structure  is  so 
arranged  that  a  series  of  rhythmic  contractions  at  short  intervals, 
goes  on  continuously  day  and  night  from  the  beginning  of  life  to 
its  close. 

The  systole  of  the  ventricles  corresponds  to  the  "heart-beat." 
It  occurs  at  perfectly  regular  intervals  in  health,  the  rate  being 


FIG.  123. 

The  right  ventricle  filled,  contracts  and  expels  blood  through  semilunar  valves 
(tricuspid  valve  closed}. — (Dalton  in  Brubaker.) 

from  sixty  to  seventy  per  minute  in  men,  and  from  seventy  to 
eighty  in  women.  The  heart's  action  is  more  rapid  in  the  upright 
position  than  in  sitting  or  lying,  and  is  increased  by  any  exercise, 
however  gentle.  Excitement  or  emotion  will  quicken  it  at  once, 
and  it  is  always  faster  in  children,  being  about  one  hundred  and 
forty  in  the  newly  born  and  reaching  an  average  rate  of  ninety 
to  one  hundred  at  the  age  of  three  years;  ninety  in  youth,  sev- 
enty in  adults,  and  eighty  in  old  age.  The  innervation  of  the 
heart  is  described  on  pages  185,  186. 

The  Pulse. — The  effect  of  the  heart-beat  upon  the  current  of 
the  blood  may  be  felt  in  the  arteries,  which  are  distended  for  an 
instant  by  the  blood  forced  into  them  as  the  ventricles  contract. 


182 


ANATOMY   AND    PHYSIOLOGY 


This  gives  the  effect  of  a  beating  in  the  arteries,  which  is  called  the 
pulse.  The  pulse-rate  corresponds  with  the  heart-beat;  therefore, 
the  rate  and  force  of  the  heart's  action  are  judged  by  means  of  the 
pulse. 

The  Heart  Sounds 

The  action  of  the  heart  causes  certain  sounds,  named  the  first 
and  second.  The  first  accompanies  the  sudden  closure  of  the  tri- 
cuspid  and  mitral  valves,  as  the  ventricles  contract.  It  is  the 


UPPER   ATTACHMENT 
OF    PERICARDIUM 


BRANCHES    OF   PUL 
MONARY    ARTERY 

AORTA--, 


BRANCHES    OF 
LMONARY  ARTERY 
-PULMONARY 
ARTERY 


DIAPHRAGM  PERICARDIUM 


RIGHT         ATTACHMENT   OF 
VENTRICLE       PERICARDIUM 
TO  DIAPHRAGM 


DIAPHRAGM 


FIG.  124. — The  heart  in  situ.     The  pericardium  has  been  cut  open  in  front,  and 

reflected.— (Testut.) 

systolic  sound — caused  by  the  systole  of  the  ventricles.  The  sec- 
ond accompanies  the  sudden  closure  of  the  semilunar  valves.  It 
is  the  diastolic  sound,  occurring  with  the  diastole  of  the  ventricles. 
The  first  or  systolic  sound  is  the  louder  and  larger,  being  due  to 
the  contracting  of  muscle  fibers  as  well  as  to  closure  of  valves. 
The  second,  diastolic  sound  is  short  and  sharp,  due  to  valve  closure 
only.  The  two  sounds  are  compared  to  the  spoken  words — lubb 
dupp. 


THE    PERICARDIUM  l83 

When  the  blood  is  forced  into  the  elastic  arteries  by  a  contraction  or 
beating  of  the  heart  it  stretches  them.  When  the  contraction  is  ended,  the 
wall  of  the  artery  recoils  and  there  is  a  setting  back  of  the  blood  for  an  instant 
toward  the  heart,  but  it  is  stopped  by  the  closing  semilunar  valves,  which  thus 
make  the  second  sound. 

Clinical  note. — If  the  valves  of  the  heart' are  rough,  the  sounds  are  changed 
by  a  "murmur."  If  they  cannot  close  perfectly,  a  portion  of  the  blood  will 
flow  backward  instead  of  going  forward,  and  this  is  regurgitation.  This,  also, 
changes  the  sound  of  a  valve  and  causes  a  murmur. 

The  pericardium  (Fig.  124). — A  loose  serous  sac  enclosing  the 
heart.  The  layer  which  closely  covers  the  heart,  or  the  visceral 
layer,  is  the  epicardium.  It  covers  the  aorta  and  pulmonary  arte- 
ries for  about  one  inch,  then  leaves  them  to  become  the  parietal 
layer  or  lining  of  the  fibrous  sac  which  encloses  the  whole,  and 
which  is  closely  attached  to  the  diaphragm  below  and  the  great 
vessels  above.  A  small  quantity  of  pericardial  fluid  prevents  fric- 
tion between  the  surfaces,  as  the  smoothly  covered  heart  beats  in 
the  smoothly  lined  cavity;  this  increases  in  inflammation  of  the 
pericardium,  or  pericarditis,  and  it  is  sometimes  necessary  to 
remove  it  by  tapping. 

REVIEW. — PRINCIPAL  POINTS  OF  INTEREST  IN  THE  HEART 
RIGHT  AURICLE 

Openings  of  two  large  veins  bringing  blood  from  the  body. 
Opening  of  coronary  sinus  bringing  blood  from  the  heart  itself. 
Oval  fossa  and  annulus  ovalis  (or  oval  ring). 
Eustachian  valve  (or  valve  of  inferior  vena  cava). 
Tricuspid  orifice  with  tricuspid  valve. 

RIGHT  VENTRICLE 

Tricuspid  orifice  and  tricuspid  valve. 
Opening  for  pulmonary  artery,  and  pulmonary  valves. 
Trabeculae  carneae  (fleshy  bands),  and  the  tendinous  cords  con- 
necting them  with  tricuspid  valve. 

LEFT  AURICLE 

Openings  of  three  or  four  pulmonary  veins. 
Mitral  orifice  with  bicuspid  (or  mitral)  valve. 


1 84 


ANATOMY   AND    PHYSIOLOGY 


LEFT  VENTRICLE 

Mitral  orifice  and  bicuspid  valve. 
Opening  for  aorta  and  aortic  valves. 

Trabeculae  carneae  and  the  tendinous  cords  connecting  them 
with  the  bicuspid  valve. 


THE  COURSE  OF  THE  BLOOD  THROUGH  THE  HEART 

Resume. — The  blood  enters  the  right  auricle,  passes  down  into 
the  right  ventricle,  and  out  through  the  pulmonary  artery  to  the 


Left  carotid  artery 

Left  subclavia 
artery 


Aorta 


Pulmonary  artery 

Pulmonary  veins 
from  left  lung 

Left  auricle 


Coronary  vessels 


Anonyma 


Superior  vena  cava 


Pulmonary  veins 
from  right  lung 

Right  auricle 


Inferior  vena  cava 


-  Coronary  artery 


FIG.  125. — POSTERIOR  SURFACE  OF  HEART. 
Pulmonary  veins  bringing  pure  blood  to  left  auricle. — (Morris'  Anatomy.) 

lungs;  it  returns  by  the  pulmonary  veins  to  the  left  auricle,  passes 
down  into  the  left  ventricle,  and  out  through  the  aorta  to  every 
part  of  the  body,  from  which  it  is  returned  by  two  large  veins  to 
the  right  auricle  again. 


CARDIAC    NERVES  185 

The  course  from  the  right  ventricle  through  the  lungs  and  back 
to  the  left  auricle  is  called  the  pulmonary  circulation  (Figs.  125  and 
1 60). 

The  course  from  the  left  ventricle  through  the  entire  body  or 
" system"  and  back  to  the  right  auricle  is  called  the  systemic 
circulation  or  main  circulation  (Fig.  126). 

Important  notes. — Pure  blood  is  carried  from  the  heart  through  the 
systemic  arteries  to  all  tissues  in  the  body  to  nourish  them.  This  blood  is 
called  arterial  blood;  it  is  bright  red  in  color.  The  term  pure  blood  and 
arterial  blood  are  used  to  signify  one  and  the  same  thing. 

Impure  blood  from  the  tissues  of  the  body  is  returned  to  the  heart  by  the 
systemic  veins.  It  is  called  venous  blood;  it  is  purple-red  or  blue  in  color  and 
contains  waste  matters.  The  terms  impure  blood  and  venous  blood  are  used  to 
signify  one  and  the  same  thing. 

The  venous  blood  from  the  body  is  poured  into  the  right  side  of  the  heart, 
from  which  the  pulmonary  artery  conveys  it  to  the  lungs.  Consequently  the 
pulmonary  artery  is  unlike  others,  because  it  carries  venous  blood  from  the 
heart;  and  the  pulmonary  veins  are  unlike  others  because  they  carry  arterial 
blood  to  the  heart. 

Innervation  of  the  heart. — As  already  mentioned,  p.  176,  the 
heart  muscle  or  myocardium  has  a  structure  peculiar  to  itself. 
Anatomically  its  fibers  differ  from  those  of  other  muscles  in  size 
and  arrangement;  physiologically  it  is  unlike  any  other  striped 
muscle  in  the  body,  being  involuntary  although  striped.  Cardiac 
muscle  responds  to  the  stimulus  brought  by  two  sets  of  nerves, 
called  accelerator  and  inhibitor  nerves.  By  the  accelerator  nerves 
the  rapidity  of  the  heart-beat  is  increased;  by  the  inhibitors  it  is 
slowed.  These  nerves  are  branches  of  the  pneumogastric  or  vagus 
nerve.  A  long  unsettled  question  is,  whether  in  the  absence  of 
these,  the  heart  would  still  beat  under  the  chemical  stimulus  alone 
of  tissue  change.  Years  of  experimentation  and  observation 
incline  scientists  to  believe  that  this  is  possible. 

The  heart  muscle  of  cold-blooded  animals  performs  rhythmic  contractions 
for  several  hours  after  removal  from  the  body;  to  insure  this  action  it  is  only 
necessary  to  keep  it  moistened  in  a  mixture  of  calcium,  potassium,  and  sodium 
salts  in  solution.  The  chemical  action  between  this  fluid  and  that  within  the 
cells  is  sufficient  to  produce  contractions,  following  each  other  in  rhythmic 
order. 

So  in  life,  an  interchange  of  chemical  products  between  lymph  and  cell 
contents  may  furnish  a  stimulus  which  keeps  the  heart  in  action,  the 


1 86  ANATOMY   AND    PHYSIOLOGY 

function  of  the  nerves  being  to  accurately  regulate  the  rate  at  which  con- 
tractions.occur.  This  is  the  myogenic  theory  of  the  cause  of  the  heart  beat. 
Another  theory,  not  so  generally  held,  is  the  neurogenic,  which  assumes  a 
special  nerve  system  in  the  myocardium,  acting  automatically  and  regulated 
or  modified  by  accelerator  and  inhibitor  nerves  as  above  described. 

The  velocity  of  the  normal  blood  current  is  greatest  in  the  larger 
arteries  and  least  in  the  capillaries.  It  increases  in  the  larger 
veins  but  never  equals  that  in  the  arteries.  The  time  required  for 
the  entire  circuit  from  heart  to  heart  again,  is  about  twenty-eight 
seconds,  or  approximately,  in  the  time  of  twenty-six  to  twenty- 
eight  heart-beats. 

The  onward  flow  of  the  current,  as  it  is  expelled  from  the  heart, 
is  assisted  by  i,  the  elastic  recoil  of  the  arterial  walls  (after  the 
stretching  caused  by  the  blood  which  is  pumped  into  them  with 
each  systole),  2,  the  pressure  of  contracting  muscles  on  the  veins, 
forcing  the  blood  toward  the  heart,  3,  the  intake  of  breath  (or 
aspiration  of  the  thorax)  when  the  auricles  are  opened  to  receive 
blood,  and  4,  the  valves  of  the  veins  which  allow  the  blood  to  flow 
onward  but  not  backward. 

The  act  of  aspiration  is  very  closely  associated  with  circulation; 
deep  breathing  alone  will  promptly  quicken  the  action  of  the  heart 
and,  consequently,  the  velocity  of  the  stream. 

Variations  due  to  emotion,  excitement,  etc., — have  been  al- 
luded to.  Blood  pressure  will  be  considered  in  Chapter  XII. 

The  total  quantity  of  blood  is  estimated  at  about  one-twelfth 
of  the  body  weight  Roughly  speaking,  it  is  distributed  (in  a 
state  of  rest)  as  follows: — one-quarter  in  the  muscles,  one-quarter 
in  the  liver,  one-quarter  in  the  heart,  lungs,  arteries  and  veins,  one- 
quarter  in  other  organs.  Of  course,  during  the  activity  of  any  spe- 
cial part  of  the  body,  as  for  example,  in  the  digestive  system — the 
proportions  are  changed,  as  the  most  active  organs  require  most 
blood,  leaving  less  for  the  others  at  that  time. 


CHAPTER  XI 
THE  CIRCULATION  OF  BLOOD 

THE  PULMONARY  CIRCULATION 

This  is  the  circulation  of  the  blood  through  the  lungs,  that  it 
may  become  aerated  or  purified. 

The  pulmonary  artery  leaves  the  right  ventricle,  carrying 
impure  blood,  and  soon  divides  into  two  branches,  the  right  and 
left  pulmonary  arteries  (one  for  each  lung),  which  break  up  into  a 
capillary  network  around  the  air  cells.  From  this  network  veins 
arise  which,  by  uniting,  form  two  from  each  lung,  making  the  four 
pulmonary  veins  carrying  purified  blood  to  the  left  side  of  the  heart. 
They  enter  the  left  atrium. 

THE  SYSTEMIC  CIRCULATION 

This  is  the  circulation  of  the  blood  through  the  entire  body  or 
"system/7  that  it  may  nourish  the  tissues  and  organs  (Fig.  126). 

Arteries  of  the  Systemic  Circulation1 

The  aorta  (Fig.  127),  having  received  pure  blood  from  the  lungs, 
leaves  the  left  ventricle,  arches  over  the  root  of  the  left  lung  to  the 
left  side  of  the  fourth  thoracic  vertebra,  then  (gradually  coming 
to  the  front  of  the  spinal  column)  passes  down  through  the 
diaphragm,  and  ends  by  dividing  at  the  fourth  lumbar  vertebra 
(a  little  below  the  level  of  the  umbilicus).  Thus  it  consists  of 
three  portions:  the  arch,  the  thoracic  aorta,  and  the  abdominal 
aorta. 

The  arch  of  the  aorta  extends  from  the  heart  to  the  body 
(lower  border)  of  the  fourth  thoracic  vertebra.  It  reaches 
almost  as  high  as  the  sternal  (or  jugular)  notch. 

It  may  be  felt  in  thin  persons  by  pressing  the  finger  tip  down  behind  the 
bone. 

1  The  names  of  all  of  the  arteries  are  given  in  tabular  form  on  page  3  79.  Only 
the  principal  ones  are  here  described. 

187 


i88 


ANATOMY   AND    PHYSIOLOGY 


FIG.  126. — SCHEME  OF  SYSTEMIC  CIRCULATION. 
Arteries  colored  red;  veins,  blue. 


ARTERIES    AND   VEINS 


189 


RIGHT    COMMON 
CAROTID 

Jugular  vein 


Right  lymph 
atic  duct 


Inferior  vena 
cava 


Abdominal 
vessels 


LEFT  COMMON 
CAROTID 

Vagus  nerve 


Thoracic  duct 
L.  V.  anonyma 


FIG.  127. — THE  AORTA,  SHOWING  THE  THREE  PORTIONS — (Morris.) 


ANATOMY  AND   PHYSIOLOGY 


Branches  of  the  arch  in  their  order: 

Two  coronary  (right  and  left),    .to  heart  muscle  (Fig.  119). 

[  Right  subclavian  to  right 

upper  extremity. 
Right  common   carotid 

right  head  and  neck. 

One  left  common  carotid  ....    to  left  head  and  neck. 
One  left  subclavian    .......    to  left  upper  extremity. 


One  anonyma,  i|  inches  long 


to 


Phrenic  nerve 
Subclavian  artery  - 
Subclavian  vein 


Anterior  intercostal 
branch 


Branch  of  mammary 


Common  carotid 

Internal  jugular  vein 
Subclavian  vein 
Scalenus  anterior  muscle 

—  Sternum 


I  Perforating  branches 
(supplying  mam- 
mary gland) 


Superior    epigastric,   running 
down  from  internal  mammary 


Inferior  epigastric,  running 
up  from  external  iliac 


FIG.  128.— SHOWING  SUBCLAVIAN  ARTERY  AND  TWO  OF  ITS  BRANCHES 
(Thyroid  axis  and  internal  mammary). — (Morris.) 

THE  PRINCIPAL  ARTERIES  or  THE  UPPER  EXTREMITY 

The  subclavian  artery  (Fig.  128)  passes  out  over  the  first  rib 
and  under  the  clavicula  (therefore  subclavian)  to  the  axilla,  or 
armpit.  The  brachial  plexus  lies  above  it  in  the  neck,  and  the 


AXILLARY   ARTERY 


IQI 


subclavian  vein  is  in  front  of  it.  The  right  subclavian  is  a  branch 
of  the  anonyma.  Both  subclavians  end  at  the  lower  border  of  the 
first  rib. 

Branches. — The  vertebral  branch  runs  upward  through  trans- 
verse processes  of  the  vertebrae  to  the  brain. 

The  internal  mammary  branch  runs  downward  inside  the  chest 
behind  the  costal  cartilages  into  the  abdominal  wall.  It  distributes 
branches  to  the  mammary  gland  and'  to  intercostal  muscles. 


FIG.  129. — SUBCLAVIAN  AND  AXILLARY  ARTERIES. — (Testut.} 

The  thyroid  axis  is  a  short  trunk ;  it  gives  a  branch  to  the  thy- 
roid gland  and  others  to  the  neck  and  shoulder. 

An  axis  (artery)  is  a  short  vessel  dividing  at  once  into  two  or  three. 

The  axillary  artery  (Fig.  129)  is  a  continuation  of  the  sub- 
clavian. It  begins,  therefore,  where  the  subclavian  ends — in  the 
apex  of  the  axilla,  at  the  lower  border  of  the  first  rib — and  con- 
tinues through  the  axillary  space.1 

1  Axillary  space,  p.  368. 


ANATOMY  AND   PHYSIOLOGY 

Branches  (thoracic,  subscapular,  circumflex.} — To  all  structures 
around  the  axilla.  One,  the  lateral  thoracic,  gives  arteries  to  the 
mammary  gland. 

The  brachial  artery  (Figs.  129,  131)  begins  where  the  axillary 
ends,  at  the  lower  border  of  the  axilla,  or  armpit,  and  extends 


FIG.  130. — DEEP  PALMAR  ARCH. 

Made  by  continuation  of  the  radial  artery.     This  is  covered  by  the  muscles  of  the 
thenar  and  hypothenar  eminences. 

downward  in  front  of  the  arm  (with  the  biceps  muscle)  to  the  bend 
of  the  elbow,  where  it  divides  into  the  radial  and  the  ulnar  arteries. 
Its  branches  supply  the  muscles  of  the  humerus  and  the  bone 
itself.  (The  median  nerve  lies  next  to  this  artery  under  the  border 
of  the  biceps  muscle.) 


RADIAL    AND    ULNAR   ARTERIES 


193 


Axillary  artery 


Lateral  cord 


Pectoral 
muscle 


Median  nerve 
Brachial  artery 


The  radial  and  the  ulnar  arteries  pass  downward  in  the  radial 
and  ulnar  sides  of  the  fore- 
arm to  the  hands.  The  radial 
supplies  the  muscles  in  front 
of  the  radius,  and  winds  to 
the  back  of  the  wrist  to  find 
its  way  to  the  palm  by  pass- 
ing forward  between  the  first 
two  metacarpal  bones.  It 
forms  the  deep  palmar  arch, 
which  crosses  the  palm  under 
the  long  tendons  (Fig.  130). 

The  ulnar  supplies  the 
muscles  in  front  of  the  ulna, 
and  forms  the  superficial  pal- 
mar arch,  which  crosses  over 
the  long  tendons  in  the  palm 
(Fig.  131). 

Note. — The  superficial  arch 
crosses  the  palm  opposite  the 
level  of  the  web  of  the  thumb 
when  put  "on  the  stretch."  The 
deep  arch  crosses  about  a  finger- 
width nearer  the  wrist. 

The  digital  arteries  run  in  the 
sides  of  the  fingers;  they  are 
branches  of  the  superficial  arch. 

Clinical  note. — The  pulsation 
of  the  radial  artery  is  easily  felt 
above  the  wrist  in  front,  next  to 
the  tendon  of  the  radial  flexor  of 
the  wrist. 

Surgical  note. — A  direct  com- 
munication exists  between  the 
deep  and  superficial  arches,  con- 
sequently severe  hemorrhage 
easily  occurs  in  the  palm,  since 
blood  will  flow  from  radial  and 
ulnar  arteries  at  one  and  the  same 
time,  and  it  is  sometimes  neces- 
sary to  ligate  both. 


Ulnar  nerve  and 

artery 

adial  nerve  and 
artery 


Branches  to  hand 


FIG.  131. — AXILLARY,  BRACHIAL,  RADIAL  AND 
ULNAR  ARTERIES.     SUPERFICIAL  ARCH. 


IQ4  ANATOMY  AND  PHYSIOLOGY 

PRINCIPAL  ARTERIES  OF  THE  HEAD  AND  NECK 

The  common  carotid  arteries. — (Fig.  127).  The  right  is  a 
branch  of  the  anonyma;  the  left  is  directly  from  the  arch  of  the 
aorta.  They  proceed  upward  on  either  side  of  the  trachea,  with 
the  internal  jugular  vein  on  the  lateral  side  and  the  vagus  nerve 
behind  them.  They  carry  the  blood  supply  of  the  head  and  neck. 

The  common  carotid  divides  at  the  upper  border  of  the  .thyroid 
cartilage  into  internal  carotid  for  the  interior  of  the  head,  and 
external  carotid  for  the  exterior  of  the  head  and  the  neck. 


FIG.  132. — ARTERIES  OF  THE  BRAIN. — (Morris.} 
Cerebral  arteries  pass  from  the  base  of  the  brain  to  all  parts  of  the  surface. 

The  internal  carotid  is  deep  in  the  neck;  it  runs  up  to  the 
head  and  through  the  carotid  canal  into  the  cranial  cavity. 

Principal  branches. — Ophthalmic,  to  eye  and  appendages,  nose, 
and  forehead.  (The  supraorbital  artery  is  a  branch  of  the 
ophthalmic.) 

Middle  cerebral  to  the  brain,  anterior  cerebral  to  the  brain 
(Fig.  132). 


PRINCIPAL    ARTERIES    OF    THE    HEAD  195 

Note. — The  internal  carotid  makes  four  sharp  turns  after  entering  the 
carotid  canal  in  the  petrous  bone,  and  by  this  means  the  force  of  the  current 
in  this  large  vessel  is  modified  before  it  reaches  the  delicate  tissues  of  the 
brain.  The  internal  jugular  vein  and  vagus  nerve  accompany  it  in  the  neck. 

The  external  carotid  artery  supplies  the  face,  and  front  of  the 
neck  and  scalp  (Fig.  133). 

Principal  branches. — Superior  thyroid,  to  the  thyroid  gland 
and  larynx.  Lingual,  to  the  tongue  and  tonsil.  Facial  (or  external 
maxillary)  to  the  face,  soft  palate  and  tonsil.  Occipital,  to  the 
back  of  the  head  and  neck. 


FIG.  133. — FACIAL,  TEMPORAL  AND  OCCIPITAL  ARTERIES. 

Clinical  notes. — The  external  maxillary  (facial)  artery  runs  toward  the 
bridge  of  the  nose.  It  sends  two  labial  arteries  to  the  borders  of  the  lips; 
the  one  in  the  upper  lip  supplies  a  branch  to  the  septum  of  the  nose,  therefore, 
compression  of  the  upper  lip  will  sometimes  stop  "nose-bleed." 

The  lingual  artery  ends  at  the  tip  of  the  tongue,  in  a  branch  (ranine)  which 
might  be  severed  in  cutting  too  freely  for  "tongue-tie." 

Having  given  off  its  branches,  the  external  carotid  passes  into 
the  substance  of  the  parotid  gland  and  divides  into  the  temporal 
and  internal  maxillary. 

The  temporal  passes  through  the  parotid  gland  and  across  the 
zygoma  to  the  side  of  the  head,  supplying  temporal  branches  to  the 
scalp.  The  internal  maxillary  runs  between  the  muscles  of  mas- 
tication (in  the  infratemporal  fossa)  to  the  deep  parts  of  the  face, 
including  the  nose  and  pharynx.  The  dental  arteries  are  all  de- 
rived from  this  vessel. 


196  ANATOMY   AND    PHYSIOLOGY 

Collateral  Circulation. — An  important  descending  branch  of  the  occipital 
artery  runs  down  under  the  deep  muscles  of  the  neck  to  unite  with  one  de- 
rived from  a  branch  of  the  subclavian,  thus  making  a  short  route  between  the 
subclavian  and  the  external  carotid;  the  blood  can  flow  in  this  indirect  way 
to  the  head  if  the  external  carotid  be  ligated. 


PRINCIPAL  ARTERIES  OF  THE  TRUNK 

The  thoracic  aorta  extends  from  the  fourth  dorsal  vertebra 
to  the  diaphragm  (Fig.  135). 

Branches. — Intercostal,  n  pairs,  to  the  intercostal  spaces; 
bronchial  to  lung  tissues;1  pericardial  to  pericardium;  esophageal 
to  esophagus,  and  mediastinal  to  glands  and  tissues  between  the 
lungs  (in  the  mediastinum,  p.  365). 

Note. — These  aortic  intercostal  arteries  run  rather  more  than  half  way  to 
the  front,  in  grooves  under  the  borders  of  the  ribs,  accompanied  by  inter- 
costal nerves  and  veins  to  meet  intercostal  branches  of  the  internal  mammary. 

The  abdominal  aorta  extends  from  the  opening  in  the  dia- 
phragm to  the  body  (lower  border)  of  the  fourth  lumbar  vertebra— 

a  little  above  the  level  of  the  umbilicus  (Fig.  134). 

Branches. — Phrenic  to  the  diaphragm  and  lumbar  (4  pairs)  to 
the  abdominal  wall,  sacral  to  sacrum  and  rectum. 

Branches  to  viscera:  The  celiac  artery,  dividing  into  gastric,  for 
the  stomach;  hepatic,  for  the  liver;2  splenic  (or  lienal),  for  the 
spleen. 

Superior  mesenteric,  to  the  small  intestine  and  these  parts  of 
the  large  intestine,  namely — cecum,  ascending  colon,  transverse 
colon. 

Inferior  mesenteric,  to  the  remainder  of  the  large  intestine, 
namely — descending  colon,  sigmoid  colon,  rectum. 

Two  renal  arteries,  to  the  kidneys. 

Adrenal  arteries,  to  the  adrenal  bodies. 

The  ovarian  arteries,  to  the  ovaries,  or  the  spermatic  arteries  to 
the  testes. 

1  Bronchial  arteries  have  very  little  to  do  with  respiration;  they  are  the  nutrient 
arteries  of  the  lungs. 

2  The  hepatic  circulation  is  a  double  one:  Both  venous  and  arterial  blood  enter 
the  liver.     The  portal  vein  (with  products  of  digestion  for  the  liver  to  work  over)  and 
the  hepatic  artery  (with  the  oxygen  with  which  this  work  is  to  be  done)  enter  together 
through  the  portal  fissure.     (The  venous  blood  of  both  leaves  the  liver  by  hepatic 
veins,  page  209.) 


ABDOMINAL   AORTA 


IQ7 


The  ovarian  artery  runs  downward  into  the  pelvis  and  passes 
between  the  layers  of  the  broad  ligament  to  the  ovary  (p.  201), 
freely  supplying  it  and  the  Fallopian  tubes.  It  ends  by  anasto- 
mosing with  the  uterine  artery  (Figs.  134,  138). 


Cystic  artery 

Hepatic  duct 

Cystic  duct 

Common  duct 

Portal  vein 

Gastro-duodenal   branch 

Superior  pyloric   branch 

Hepatic  artery 

Right  suprarenal  vein 

Inferior  suprarenal  artery 

Renal  artery 

Renal  vein 

Inferior  vena  cava 
Kidney 


Right  spermatic  vein  :— - 


Right  spermatic  artery 
Quadratus  lumborum 

muscle 

Right  lumbar  artery  and 
left  lumbar  vein 
Ureteric  branch  of 
spermatic  artery 


Middle  sacral  vessels 


Left  lobe  of  liver 

Esophagus ,  cut. 
Left  phrenic  artery 

Right  phrenic  artery 
Superior  suprarenal 
Gastric  artery 
Inferior  suprarenal 
Splenic  artery 

Left  phrenic  vein 
Left  suprarenal  vein 
Superior  mesenteric 
artery 

Kidney 

Ureteric  branch  of  rena 

Left  spermatic  vein 

Ureter 


Left  spermatic  or 
ovarian  artery 


Inferior  mesenteric  artery 
Ureteric  branch  of 
spermatic 


Ureteric  branch  of 
common  iliac 

Common  iliac  artery 


External  iliac  artery 
Hypogastric 


FIG.  134. — BRANCHES  OF  THE  ABDOMINAL  AORTA. — (Morris.) 
Note  that  the  right  common  iliac  is  longer  than  the  lejt. 


The  spermatic  artery  runs  downward  and  along  the  brim  of  the 
pelvis  to  pass  out  through  the  inguinal  canal  with  the  spermatic 
cord;  it  continues  downward  in  the  scrotum  to  supply  the  testes. 

Special  notes. — The  superior  mesenteric  lies  between  the  layers  of  the 
mesentery.  The  inferior  mesenteric  lies  partly  in  the  left  meso-colon;  it 


198 


ANATOMY   AND   PHYSIOLOGY 


terminates  as  the  superior  hemorrhoidal  in  the  upper  part  of  the  rectum 
(Fig.  137). 

The  gastric  artery  follows  the  lesser  curve  of  the  stomach,  and  is  frequently 
called  the  coronary  artery.  The  hepatic  and  splenic  both  send  large  branches 
to  the  greater  curve  of  the  stomach,  and  also  to  the  pancreas  and  duodenum 
before  reaching  the  liver  and  spleen. 


Superior  vena 
cava 


V.  azygos  major 


Veins 


Inferior  vena 
cava 


FIG.  135. — COURSE  OF  THORACIC  AND  ABDOMINAL  AORTA. — (Morris.} 

The  abdominal  aorta  divides  (bifurcates)  at  the  lower  border  of 
the  fourth  lumbar  vertebra  into  the  right  common  iliac  and  the  left 
common  iliac  (Fig.  134). 

The  two  common  iliac  arteries  diverge  and  when  they  reach 
the  sides  (right  and  left)  of  the  lumbo-sacral  joint,  each  divides  into 
hypogastric  (or  internal  iliac)  and  external  iliac  (see  Fig.  134). 

The  hypogastric  artery  passes  into  the  pelvis  and  gives  off 


PELVIC   ARTERIES 


199 


branches  which  supply  the  parts  within  and  without  the  pelvic 
wall,  including  the  perineum,  and  all  of  the  pelvic  viscera  except 
the  ovaries.  (Branches  to  the  exterior  of  the  pelvis  pass  through 
the  sciatic  and  obturator  foramin.) 

Visceral  branches. — Middle  hemorrhoidal,  to  the  rectum. 

Vesical  (two)  to  the  bladder. 


.  Mesenteric 

vein 


Cecum 


Appendix 


Small  in- 
testine 


FIG.  136. — SUPERIOR  MESENTERIC  ARTERY  AND  VEIN. — (Morris.} 
Supplying  the  whole  of  the  small  intestine,  and  about  one-half  of  the  large  intestine. 

Uterine  to  the  uterus. 
Vaginal  (several)  to  the  vagina. 

The  uterine  artery  (Fig.  138)  passes  between  the  layers  of  the 
broad  ligament  to  the  cervix  of  the  uterus,  then  runs  upward  along 


2OO 


ANATOMY   AND    PHYSIOLOGY 


the  side  of  the  body,  supplying  it  freely  with  blood,  and  anastomos- 
ing with  the  ovarian  artery. 

The  arteries  of  the  organs  in  the  lower  part  of  the  pelvis  are 
numerous.  There  are:  three  (or  four)  vaginal  arteries,  three  (or 
more)  vesical  arteries,  three  or  more  hemorrhoidal  arteries,  all 
derived  from  the  hypogastric  or  its  branches,  except  the  superior 
hemorrhoidal  which  is  the  terminal  portion  of  the  inferior  mesenteric. 


Right  iliac 
artery 

Middle  sacral 


Colic  artery 


Iliac  vein 
Sigmoid  vessels 


Superior 
hemorrhoidal 


Rectum 


FIG.  137. — INFERIOR  MESENTERIC  ARTERY. — (Morris.} 
Supplying  a  portion  of  large  intestine  only,  ending  as  hemorrhoidal. 

There  are  also  two  perineal  arteries. 

These  all  anastomose  freely  with  each  other  and  with  other 
arteries,  so  that  a  wound  in  this  region  is  followed  by  an  abundant 
flow  of  blood  from  more  than  one  vessel. 

Note. — The  hypogastric  arteries  in  the  fetus  are  large.  After 
giving  off  their  branches  they  turn  upward  to  the  umbilicus  where 


EXTERNAL   ILIAC   ARTERY 


201 


they  leave  the  body  of  the  child,  and  become  the  two  umbilical 
arteries  twining  around  the  umbilical  vein  in  the  umbilical  cord. 
After  birth,  these  portions  of  the  vessels  no  longer  transmit  blood 
but  dwindle  to  fibrous  cords  lying  close  to  the  anterior  abdominal 
wall  (p.  356). 


Uterine     Branch  to  round 
branch  ligament 


Fimbriated  extremity  of 
Fallopian  tube 


Ovarian  artery 
Branches  of  ovarian  art. 


Cervical 

branch  of 

uterine  artery 


Uterine  artery 
ypogastric  artery 


Vaginal  arteries 


Azygos  artery  of  vagina 

FIG.  138. — UTERINE  AND  OVARIAN  ARTERIES. 

(Uterine,  a  branch  of  hypogastric;  ovarian,  a  branch  of  aorta.     Note  the  location 
of  the  ureter. — (Morris.} 


PRINCIPAL  ARTERIES  OF  THE  LOWER  EXTREMITY 

The  external  iliac  distributes  its  branches  almost  entirely  to 
the  lower  extremity.  It  is  about  four  inches  long  and  follows  the 
brim  of  the  pelvis  to  the  inguinal  ligament  where  it  becomes 
femoral. 

Collateral  circulation. — The  inferior  epigastric  branch  of  the  external  iliac 
anastomoses  with  the  superior  epigastric  branch  of  the  internal  mammary,  in 
the  substance  of  the  rectus  muscle,  thus  making  an  indirect  route  from  the 
arch  of  the  aorta  to  the  iliac  vessels  if  the  abdominal  aorta  or  iliac  artery  be 
ligated. 


202 


ANATOMY  AND   PHYSIOLOGY 


Anterior  tibial 
nerve 


Anterior  tibial 
artery 


•  Gluteal  n. 


Sciatic  n. 


Popliteal  artery 
Tibial  n. 

Peroneal  n. 


Ant.  tib.  artery 


Tibial  n. 

Post.  tib.  artery 


FIG.  139. — THE  FEMORAL  ARTERY.  FIG.  140.— THE  POPLITEAL  ARTERY. 


THE  VEINS  203 

The  femoral  artery  (Fig.  139)  is  a  continuation  of  the  external 
iliac,  passing  through  the  femoral  trigone  and  the  adductor  canal  to 
the  popliteal  space,1  where  it  becomes  the  popliteal  artery.  Its 
branches  supply  the  skin  and  fascia  of  the  lower  abdomen  and 
external  genital  organs,  and  all  structures  of  the  front  and  sides 
of  the  thigh.  The  largest  branch  is  called  the  deep  femoral, 
which  lies  close  to  the  medial  side  of  the  femur  and  gives  three 
perforating  branches  to  pass  through  the  adductor  magnus  muscle 
and  supply  the  back  of  the  thigh. 

Note. — The  femoral  vein  is  on  the  medial  side  of  the  femoral 
artery  until  it  reaches  the  popliteal  space. 

The  popliteal  artery  is  a  continuation  of  the  femoral,  beginning 
at  the  end  of  the  adductor  canal  (the  opening  in  the  adductor 
magnus)  and  running  through  the  popliteal  space.  Its  branches 
supply  the  boundaries  and  floor  of  the  space  and  the  knee-joint; 
it  divides  into  anterior  and  posterior  tibial  arteries  (Fig.  140). 

The  anterior  tibial  (Fig.  139)  comes  forward  between  the 
tibia  and  fibula,  supplying  the  front  of  the  leg;  it  then  becomes 
the  dorsalis  pedis  (upon  the  dorsum  of  the  foot) ,  ending  between 
the  first  and  second  toes.  The  anterior  tibial  passes  in  front  of 
the  ankle-joint,  with  the  long  tendons  of  the  toe  muscles. 

The  posterior  tibial  (Fig.  140)  supplies  the  back  of  the  leg  and 
sole  of  the  foot.  It  lies  between  the  calf  muscles  and  the  deep 
muscles,  and  runs  behind  the  medial  malleolus,  dividing  then  into 
medial  and  lateral  plantar  arteries  for  the  medial  and  lateral  por- 
tions of  the  sole,  or  plantar  region  (Fig.  141) 


The  Veins 

All  veins2  run  toward  the  heart. 

Beginning  as  very  small  vessels  formed  by  the  union  of  capil- 
laries, they  unite  and  reunite  until  they  make  two  sets  of  larger 
vessels  called  the  deep  and  superficial  veins. 

The  deep  veins  accompany  arteries,  being  enclosed  in  the  same 
sheath  with  them,  and  receiving  veins  corresponding  to  the 
branches  of  these  arteries.  Arteries  of  medium  size  usually  have 

1  See  p.  371,  Popliteal  Space. 

8  The  names  of  all  of  the  veins  are  given  in  tabular  form  on  page  379.     Only  the 
principal  ones  are  here  described. 


2O4 


ANATOMY   AND    PHYSIOLOGY 


two  companion  veins  (or  venae  comites) ;  large  ones  have  but  one, 
and  it  sometimes  bears  a  name  differing  from  that  of  the  artery. 
(Example — internal  carotid  artery,  internal  jugular  vein.) 

The  superficial  veins  do  not  usually  accompany  arteries. 
They  lie  in  the  superficial  fascia,  gathering  blood  from  skin  and 
fascia,  and  many  of  them  are  called  cutaneous.  Very  frequently 
the  deep  and  superficial  veins  communicate,  through  short  con- 
necting branches. 


PRINCIPAL  VEINS  OF  THE  HEAD  AND  NECK 

Deep. — From  the  deep  face  and  cranial  cavity;  they  empty 
into  the  internal  jugular  vein  (Figs.  127,  145). 

The  internal  jugular  is  a  continuation  of 
the  transverse  sinus  (a  venous  channel  inside 
the  skull,  which  ends  at  the  jugular  fora- 
men). This  vein  lies  on  the  lateral  side  of 
the  internal  carotid  artery  in  the  upper  part 
of  the  neck,  and  further  down  at  the  side  of 
the  common  carotid  artery,  with  the  vagus 
nerve  between  and  behind  them.  (Fig.  127.) 
It  ends  by  uniting  with  the  subclavian  vein. 
Superficial. — From  the  scalp,  ear,  and 
face,  bearing  the  names  of  the  arteries  (usu- 
ally) ;  they  empty  into  the  external  jugular 
vein  which  opens  into  the  subclavian. 

There  are  many  veins  in  the  spongy  bone  be- 
tween the  compact  layers  of  cranial  bones,  and  these 
communicate  by  emissary  veins  with  the  sinuses  and 
also  with  the  scalp  veins. 


FIG.  141. — DEEP  AR- 
TERIES IN  SOLE  OF 
FOOT. 

i,  Medial  plantar; 
2,  lateral  plantar. — 
Holden.} 


PRINCIPAL  VEINS  OF  THE  UPPER  EXTREMITY 


Deep. — From  the  hand  and  wrist;  they 
form  ulnar  and  radial  veins  (running  with 
arteries  of  the  same  name)  which  unite  to  form  brachial  veins. 

The  brachial  veins  in  turn  unite  to  form  the  axillary,  and  the 
axillary  becomes  subclavian  (Fig.  126). 


SUPERFICIAL    VEINS 


205 


FIG.  142. — SUPERFICIAL  VEINS, 
UPPER  EXTREMITY. 


FIG.  143. — SUPERFICIAL  VEINS, 
LOWER  EXTREMITY. 


206 


ANATOMY  AND   PHYSIOLOGY 


The  external  jugular  vein  empties  into  the  subclavian  at  about  the  middle 
of  the  clavicula.     It  is  easily  seen  through  the  platysma  muscle. 

Superficial. — From  fore  arm; 
groups  of  veins,  both  anterior  and 
posterior,  form  two,  called  the  basilic 
and  cephalic,  which  empty  into  the 
axillary  vein. 

Median  veins  in  front  of  the  elbow  con- 
nect the  basilic  and  the  cephalic  (Fig.  142). 

The  subclavian,  having  gathered 
blood  from  the  entire  upper  extrem- 
ity, unites  with  the  internal  jugular 
to  form  the  anonyma  vein;  the  an- 
onyma  veins  (right  and  left)  unite  to 
form  the  superior  vena  cava  (Fig. 
127). 

The  left  anonyma  vein  is  the 
longer  of  the  two,  since  it  must 
cross  to  the  right  side  to  join  the 
right  vein. 

The  Superior  Vena  Cava 

The  superior  vena  cava  is  formed 
by  the  union  of  the  two  anonyma 
veins.  It  lies  on  the  right  side  of 
the  arch  of  the  aorta,  and  opens  into 
the  right  atrium  of  the  heart 
(Fig.  126). 


Great 

or  long 

saphena 

vein 


VEINS  OF  THE  THORAX 
Blood  from  all  of  the  intercostal 
veins  (except  in  the  first  space) 
finally  reaches  the  great  azygos  vein, 
which  opens  into  the  superior  vena 
cava  (Fig.  135,  azygos  major). 

The  blood  of  the  heart  itself  is 
returned  directly  to  the  right  atrium 
by  a  coronary  vein  called  the  coronary 
sinus.  All  other  thoracic  organs  return  their  blood  to  azygos 
veins  and  these  to  superior  vena  cava. 


FIG.  144. — SUPERFICIAL  VEINS, 
ANTERIOR. 


VEINS   OF  LOWER  EXTREMITY 


207 


SUMMARY 

The  venous  blood  from  all  structures  above  the  diaphragm 
(except  the  heart)  is  returned  through  the  superior  vena  cava  to 
the  right  heart  (right  atrium). 


PRINCIPAL  VEINS  OF  THE  LOWER 
EXTREMITY 

Deep. — From  the  dorsum  of  the  foot  the 
veins  form  the  anterior  tibial  veins ;  from  the 
sole  of  the  foot,  the  posterior  tibial. 

The  tibial  veins  run  upward  in  the  leg 
and  unite  to  form  the  popliteal,  which  con- 
tinues as  the  femoral,  and  these  two  veins 
receive  others  corresponding  in  name  to 
the  branches  of  the  arteries  which  they 
accompany. 

Superficial. — From  the  lateral  part  of 
the  foot  and  leg,  by  the  small  saphena  vein, 
to  the  popliteal  (Fig.  143). 

From  the  dorsum  and  medial  part  of 
the  foot  and  leg  by  the  great  saphena  vein 
to  the  femoral,  passing  through  the  oval 
fossa  in  the  fascia  lata,  below  the  inguinal 
ligament  (Fig.  144).  The  femoral  vein 
becomes  external  iliac. 


VEINS  OF  THE  PELVIS  AND  ABDOMEN         FIG.  145.  —  SHOWING 

FORMATION   OF  THE  LARGE 
The   veins   of   the  pelvic  organs  are  VEINS. 

large  and  numerous. 


In  the  vaginal  walls  and  around  the  subclavian;  5,6,  int.  and  evt. 

.      f     .  .  ,  .  jugular     veins;     8,    inferior 

lower  end  of  the  vagina,  also  in   the  rec-  vena  cava;  14,  common  iliac 


turn  especially,  they  form  close  networks 
or  plexuses  which  when  wounded  bleed 
profusely.  The  veins  of  the  anal  canal  are  prone  to  become  con- 
gested and  assume  a  varicose  condition  constituting  hemorrhoids. 
The  pelvic  veins  empty  into  the  hypogastric,  and  the  hypo- 
gastric  and  external  iliac  veins  unite  to  form  the  common  iliac. 


208  ANATOMY   AND   PHYSIOLOGY 

The  right  and  left  common  iliac  veins  unite  to  form  the 
inferior  vena  cava  (Fig.  134). 

The  Inferior  Vena  Cava 

This  is  formed  by  the  union  of  the  two  common  iliac  veins  at 
the  right  side  of  the  bifurcation  of  the  abdominal  aorta  (p.  197) 


FIG.  146. — SCHEME  OF  FORMATION  OF  PORTAL  VEIN,  BY  VEINS  FROM  SPLEEN, 
STOMACH  AND  INTESTINES. 

(level  of  the  lower  border  of  the  fourth  lumbar  vertebra).     It  runs 
upward  through  the  abdomen,  on  the  right  side  of  the  aorta, 


PORTAL   CIRCULATION  2OQ 

close  to  the  spinal  column,  to  pass  through  the  diaphragm  and 
enter  the  pericardium  and  right  atrium  of  the  heart. 

From  the  abdominal  walls  the  phrenic  and  lumbar  veins  open 
into  the  inferior  vena  cava. 

From  abdominal  viscera  the  renal  and  adrenal  veins  open  into 
the  inferior  vena  cava. 

The  right  ovarian  and  right  spermatic  veins  open  into  the  in- 
ferior vena  cava;  the  left  ovarian  and  left  spermatic  veins  open  into 
the  left  renal  vein  which  carries  their  blood  to  the  inferior  vena 
cava. 

The  splenic  (or  lienal),  gastric,  and  mesenteric  veins  form  the 
portal  vein,  which  is  four  inches  long  and  enters  the  liver  at  the 
transverse  fissure  or  porta  (Figs.  112,  146). 

THE  PORTAL  CIRCULATION 

This  is  the  circulation  of  venous  blood  through  the  liver.  The 
portal  vein  bears  the  products  of  digestion  from  stomach  and 
intestines;  entering  the  liver  at  the  porta  or  gate,  it  divides  into 
branches  which  form  an  extensive  network  in  its  substance. 

Having  been  distributed  through  these  fine  capillaries,  the 
blood  leaves  the  liver  by  the  hepatic  veins,  which  open  directly 
into  the  inferior  vena  cava. 


Vessels  passing  through  the  porta  (or 
transverse  fissure)  of  the  liver: 


Entering 


Hepatic  artery. 

Portal  vein. 

Two  hepatic  ducts. 


Lymphatics. 


All  of  the  hepatic  veins  leave  the  liver  at  the  back,  opening  at  once  into 
a  larger  vein  running  to  the  heart  (the  inferior  vena  cava).  The  great 
quantity  of  venous  blood  which  the  liver  contains  gives  to  it  its  dark  color. 

SUMMARY 

The  venous  blood  from  all  structures  below  the  diaphragm 
(except  upper  lumbar  walls)  is  returned  through  the  Inferior 
Vena  Cava  to  the  heart  (right  atrium). 

THE  FETAL  CIRCULATION 

The  fetus  is  nourished  by  blood  brought  from  the  uterine 
(placental)  arteries  of  the  mother,  through  a  special  vessel  called 
14 


210  ANATOMY   AND    PHYSIOLOGY 

the  umbilical  vein.  After  circulating  in  the  body  of  the  child 
it  is  returned  to  the  placenta  by  two  special  vessels  called  the 
umbilical  arteries,  branches  of  the  hypogastrics.  (They  shrink 
to  fibrous  cords  after  birth,  which  may  be  seen  on  the  interior 
surface  of  the  abdominal  wall.) 

During  intrauterine  life  the  lungs  do  not  contain  air,  therefore, 
the  interchange  of  oxygen  and  carbon  dioxid  in  the  blood  must  be 
accomplished  elsewhere.  This  also  is  brought  about  by  means  of 
the  placental  vessels. 


Opening  closed  by 
tricuspid  valve    - 
Foramen  ovale 

Coronary  sinus 

Location  of  Eu- 

stachian  valve 


FIG.  147. — INFANT'S  HEART. 
Showing  interior  of  right  atrium. — (H olden.} 

The  plan  of  fetal  circulation  requires  still  other  special  pro- 
vision, namely: 

The  foramen  ovale. — An  opening  in  the  septum  between  the 
two  atria  (Fig.  147).  It  closes  after  birth. 

The  Eustachian  valve. — A  fold  of  endocardium  in  the  R. 
atrium  (so  placed  as  to  direct  the  blood  from  the  inferior  vena 
cava  through  the  foramen  ovale).  This  remains  after  birth. 

The  ductus  arteriosus. — A  short  trunk  (1/2  inch  long)  which 
connects  the  pulmonary  artery  with  the  arch  of  the.  aorta.  This 
shrinks  to  a  cord  after  birth. 

The  course  of  the  blood  is  as  follows:  Arterial  blood  is  brought 
through  the  umbilical  vein  which  enters  the  body  at  the  umbilicus, 
runs  upward  under  the  liver  (giving  branches  to  that  organ)  and 
terminates  by  opening  into  the  inferior  vena  cava,  just  below 
the  diaphragm.  This  blood  flows  at  once  into  the  right  atrium 
of  the  heart,  where  it  is  guided  by  the  Eustachian  valve  through 


THE    PLACENTA 


211 


FIG.  148. — THE  FETAL  CIRCULATION. — (Morris.} 


212  ANATOMY   AND    PHYSIOLOGY 

the  foramen  ovale  into  the  left  atrium;  from  there  it  passes  into 
the  left  ventriculum  and  through  the  aorta,  to  be  distributed. 

The  greater  portion  of  this  current  goes  to  the  head  and  upper 
extremities,  from  which  it  returns  to  the  right  atrium  again  and 
passes  down  into  the  right  ventriculum;  thence  into  the  pulmonary 
artery,  but  not  to  the  lungs  (except  a  very  small  portion);  it  is 
delivered  instead  by  the  ductus  arteriosus  to  the  aorta  (at  a  point 
where  the  arch  begins  to  descend,  and  joins  the  small  current 
already  there,  to  supply  the  trunk  and  lower  extremities. 

The  greater  portion  of  this  blood  leaves  the  fetus  before  the 
lower  extremities  are  reached,  by  way  of  the  two  umbilical  arteries, 
and  returns  to  the  placenta  for  re-oxygenation;  while  that  which 
does  go  to  the  lower  extremities  is  later  returned  to  the  inferior 
vena  cava  to  be  again  mixed  with  blood  from  the  umbilical  vein, 
on  its  way  to  the  fetal  heart. 

The  external  iliac  supplies  the  lower  extremities  before  and 
after  birth. 

Notes. — The  liver  is  the  only  organ  to  receive  blood  just  as  it  comes  from 
the  mother;  the  baby's  liver  is  very  large.  The  head  and  upper  extremities 
are  next  supplied,  although  with  a  slight  admixture  of  venous  blood  (which 
came  through  the  inferior  vena  cava) ;  they  are  well  developed.  The  pelvis 
and  lower  extremities  receive  but  a  small  supply  of  venous  with  a  slight 
admixture  of  arterial  blood;  they  are  not  so  well  developed. 

The  placenta. — The  placenta  is  formed  in  a  portion  of  the  lining 
membrane  of  the  uterus,  by  an  intricate  arrangement  of  the  uterine 
vessels  of  the  mother  with  the  umbilical  vessels  of  the  fetus.  It  is 
here  that  the  umbilical  arteries  coming  from  the  fetus  end;  and 
the  umbilical  vein  going  to  the  fetus  arises.  Here  also  the  inter- 
change of  gases  and  of  waste  and  nutritive  matter  between  fetal 
and  maternal  blood  is  carried  on,  in  blood  spaces  of  the  placenta. 

The  umbilical  cord  connects  the  placenta  and  the  fetus.  It 
comprises  the  two  arteries  and  the  one  vein,  protected  by  a  gelat- 
inous substance  or  "  Wharton's  jelly,"  in  which  they  are  embedded. 


CHAPTER  XII 
PHYSIOLOGY  OF  THE  BLOOD 

We  have  learned  that  the  nutritious  portions  of  the  food  are, 
after  digestion,  poured  into  the  blood  and  circulated  throughout 
the  body;  also  that  cell  action  results  in  waste  which  is  returned  to 
the  blood.  Again,  that  tissue  changes  are  chemical  in  their  nature 
and  chemical  action  is  accompanied  by  heat;  this  is  imparted  to 
the  blood,  which  can  in  turn  convey  heat  to  other  parts. 

Here,  then,  are  three  important  functions  of  the  blood: 

1.  To  convey  food  (including  oxygen  from  the  lungs)  to  the 
tissues.1 

2.  To  convey  waste  (including  carbon  dioxide)  from  the  tissues. 

3.  To  equalize  the  body  temperature.     Add  to  these: 

4.  To  provide  water  for  dissolving  waste  substances  to  be 
removed  from  the  body  by  skin,  kidneys,  lungs  and  intestine. 

5.  To  be  a  medium  for  transporting  internal  secretions  (page 

263). 

6.  To  furnish  its  own  remedy  for  hemorrhage  by  bearing  the 
factors  of  coagulation.     (See  page  217.) 

(The  blood  is  a  source  of  water  supply  as  well  asfood  supply 
for  the  body.) 

The  special  functions  of  the  blood  cells  have  been  outlined, 
namely: — The  oxygen-bearing  property  of  red  cells  and  the  phago- 
cytic  power  of  the  white. 

Any  irritation  of  the  tissues  is  promptly  followed  by  an  increase 
in  the  blood  and  lymph  supply  of  the  part,  and  (if  long  continued) 
crowding  of  cells  in  the  capillaries.  The  leucocytes  put  forth  little 
prolongations  of  their  substance  which  penetrate  the  vessel  wall, 
and  gradually  the  cells  themselves  work  their  way  through.  This 
causes  a  hardened  or  indurated  condition  which  will  soon  disappear  if 
not  excessive,  but  with  severe  irritation  the  process  goes  on  to  inflam- 
mation (the  cells  crowding  each  other  to  death)  and  pus  results. 

It  is  due  to  the  character  of  the  capillary  walls  that  the  blood 
cells  can  migrate  into  the  tissues  (diapedesis).  In  case  of  bacterial 

1  It  must  not  be  forgotten  that  oxygen  plays  an  important  part  in  tissue  changes 
— hence  the  importance  of  the  blood  as  an  oxygen  carrier. 

213 


214  ANATOMY   AND   PHYSIOLOGY 

invasion,  the  leucocytes  surround  and  absorb  the  offending  organ- 
isms, thus  protecting  the  body  from  the  effects  of  their  toxins. 
This  they  are  doing  continually  because  we  are  constantly  taking 
bacteria  of  various  sorts  into  our  systems.  So  long  as  the  number 
is  not  too  great  the  phagocytes  can  take  care  of  them;  it  is  only 
when  there  are  too  many  that  they  cannot  be  overcome. 

Consisting  as  it  does  of  a  single  layer  of  endothelial  cells,  the 
capillary  wall  also  renders  possible  the  interchange  of  fluids  between 
the  blood-vessels  and  the  tissues.  This  interchange  is  accom- 
plished by  the  physical  process  of  osmosis,  which  may  be  denned 
as  the  diffusion  of  two  liquids  or  solutions  through  an  intervening 
membrane. 

Simple  diffusion  is  the  mixing  of  two  liquids  when  poured  together,  to 
form  a  uniform  solution. 

Filtration  is  the  passing  of  a  liquid  through  a  membrane  or  other  substance 
for  the  purpose  of  removing  some  portion. 

It  is  probable  that  all  three  processes  go  on  in  the  tissues. 

Clinical  note. — Two  methods  of  local  treatment  of  inflammation  are  based 
upon  the  above-named  conditions:  (i)  preventive;  (2)  remedial.  By  the 
application  of  ice  to  prevent  the  intensity  of  hyperemia  which  leads  to 
destruction  of  the  tissues,  or  by  application  of  heat  to  cause  dilation  of  sur- 
face vessels  and  relieve  it.  After  tissue  destruction  has  actually  occurred  ice 
is  no  longer  useful. 

References  have  been  made  to  the  salinity  of  the  blood  and  normal  saline 
solution,  which  is  a  solution  of  the  same  concentration  as  blood  plasma. 
Several  very  important  things  are  conditioned  by  the  normal  salinity  of  the 
blood:  (i)  The  integrity  of  the  corpuscles.  They  as  well  as  plasma  contain 
substances  which  give  them  a  certain  density.  If  the  plasma  were  a  fluid  of 
lesser  density,  its  watery  portion  would  invade  the  corpuscle  and  injure  or 
destroy  it.  If  the  plasma  were  of  greater  density,  the  water  of  the  corpuscle 
would  leave  it  and  the  cell  would  shrink.  (The  "  diffusion  streams  "  of  osmosis 
would  be  set  in  motion  in  the  effort  to  equalize  the  densities  of  cell  and  blood, 
the  outer  portion  of  cell  protoplasm  representing  a  membrane.)  • 

The  subject  of  osmosis  is  considered  on  page  1 70. 

Hypodermoclysis. — This  is  the  injecting  of  a  watery  solution 
of  certain  salines  into  the  fascia  under  the  skin,  for  the  purpose 
of  adding  fluid  to  the  blood,  by  absorption  from  the  tissue. 
From  the  preceding  paragraph  one  understands  why  the  fluid 
injected  must  be  a  normal — or  physiologic  salt  solution — that 
is,  it  must  be  of  the  same  density  as  the  blood  plasma.  (The 
normal  salt  solution,  better — physiologic  salt  solution,  must  con- 
tain nine-tenths  of  i  per  cent,  of  salines.) 


BLOOD    TRANSFUSION  215 

3.  Transfusion  of  physiologic  salt  solution,  or  injecting  directly 
into  a  vein.  A  more  serious  measure.  Here  the  blood  stream  is 
invaded  at  once  and  good  or  bad  effects  are  caused  promptly. 
Accuracy  is  essential,  that  the  injected  fluid  should  be  exactly  of 
the  right  density  and  that  nothing  else  whatever  should  enter  the 
vein,  lest  clot  formation  occur. 

Why  are  saline  fluids  introduced  into  the  vessels?  (i)  To 
restore  volume  to  the  blood  and  maintain  proper  tension  in  the  ves- 
sels, thus  assisting  the  action  of  the  heart;  (2)  to  secure  the  tis- 
sues from  loss  of  water  and  injuries  due  to  disturbances  in  osmotic 
pressure;  (3)  to  insure  the  distribution  of  normal  red  cells;  (4) 
to  dilute  the  poisons  which  are  not  eliminated  during  processes  of 
disease,  as  in  uremia. 

Direct  transfusion  of  blood  is  accompanied  by  a  special  danger 
because  it  is  possible  that  the  blood  cells  of  one  individual  may 
act  injuriously  upon  those  of  another,  causing  disintegration  or 
hemolysis  of  red  cells.  (See  Glossary.) 

The  blood  of  the  donor  (the  person  who  gives  it)  may  be  hemolytic  to 
that  of  the  patient;  that  is,  it  will  cause  hemolysis  of  the  patient's  cells. 
Still  more  to  be  avoided  is  the  situation  where  the  patient's  blood  is  hemolytic 
to  that  of  the  donor.  Fortunately  this  accident  need  no  longer  occur,  since 
laboratory  tests  can  be  made  which  will  insure  the  selection  of  a  donor  whose 
blood  will  agree  with  that  of  the  patient. 

Blood  transfusion  is  resorted  to  after  severe  hemorrhage,  also 
in  certain  diseases,  as  leukemia,  in  which  the  red  cells  are  dimin- 
ished in  number. 

Rapidity  of  heart  action  does  not  necessarily  move  the  blood  any 
faster  through  the  vessels,  as  the  rapid  heart  is  frequently  a  weak 
heart.  Also  the  short  cardiac  cycle  signifies  that  the  diastole  is 
shortened;  the  chambers  cannot  receive  as  much  blood;  conse- 
quently, less  is  sent  out. 

Another  effect  of  the  weak  and  rapid  heart  is  to  deprive  it  of 
proper  resting  time.  It  wears  itself  out. 

Quite  different  is  the  normal  acceleration  of  heart  action  in  the 
course  of  muscular  exercise;  this  really  sends  the  blood  more 
abundantly  through  the  body.  The  auricles  are  well  filled,  the 
ventricles  contract  forcibly  and  the  cardiac  cycle,  although  short, 
is  efficient. 

Variations  in  the  blood  flow  are  influenced  in  the  vessels  by 


2l6  ANATOMY   AND   PHYSIOLOGY 

i)aso-motor  nerves.  By  vaso-dilators  the  arterioles  are  enlarged, 
allowing  a  free  passage  of  blood ;  by  the  vase-constrictors  they  are 
made  smaller,  thus  cutting  down  the  quantity  of  blood  in  a  given 
area.  A  certain  balance  of  tone  in  the  blood-vessel  system  is  neces- 
sary to  proper  action  of  the  heart  and  to  the  process  of  osmosis. 

The  moving  blood  current  exerts  a  certain  amount  of  pressure 
upon  the  vessel  walls;  this  (in  health)  is  normal  blood  pressure- 
estimated  by  the  experienced  touch,  but  far  more  accurately  by 
instruments  designed  for  the  purpose,  whereby  the  pressure  in  an 
accessible  artery  is  recorded  upon  a  graduated  scale.  The  instru- 
ment is  the  sphygmomanometer  of  which  there  are  various  designs. 

Blood  pressure  is  increased  by  an  increase  in  the  effort  of  the 
heart,  or  in  the  resistance  in  front  of  it,  or  in  the  volume  of  the 
blood.  On  the  other  hand,  pressure  is  diminished  by  diminished 
heart  force,  diminished  resistance,  diminished  volume. 

Arterial pressureis  illustrated  by  the  force  of  the  stream  spurting 
from  the  mouth  of  a  severed  artery.  In  a  small  vessel  this  is  an  in- 
terrupted force,  giving  the  appearance  of  throbbing  or  beating  in  the 
stream.  Venous  pressure  causes  the  blood  to  well  up  in  a  wound 
rapidly  but  with  a  steady  flow.  Capillary  blood  simply  oozes. 

The  cause  of  blood  pressure  is  the  resistance  in  front  of  the, 
stream  resulting  from  the  constantly  diminishing  size  of  the  arter- 
ies, reacting  to  the  attempt  to  drive  the  blood  through  them. 

Clinical  note. — In  the  processes  which  lead  to  arterio-sclerosis  the  middle 
coat  of  the  artery  is  affected,  the  loss  of  elasticity  being  the  first  element  of 
failure.  Long-continued  high  pressure  is  a  common  cause  of  arterio-sclerosis 
since  it  calls  for  increasing  action  of  the  muscle  and  elastic  fibers  in  the 
tunica  media  and  at  last  tires  them  out.  The  elasticity  of  the  vessel  wall  is 
gone;  it  can  no  longer  preserve  normal  tone;  connective  tissue  thickening 
follows  and  stiffens  the  artery.  Later,  a  uniform  hardness  may  be  caused  and 
brittleness,  of  which  a  common  result  is  rupture  and  hemorrhage.  This  may 
occur  at  any  place,  often  in  the  brain,  often  in  the  muscles  of  the  lower 
extremities. 

Arterio-sclerosis  also  interferes  with  the  interchange  between  the  blood 
and  lymph  and  the  normal  metabolism  in  the  tissues. 

A  physiologic  or  normal  high  pressure  is  caused  temporarily  by 
a  quickening  of  the  circulation,  as  in  vigorous  muscle  exercise: 
by  nervous  excitement,  as  fright,  anger,  joy,  etc. 

Pathologic  or  abnormal  high  pressure  may  be  caused  by  poisons, 
either  swallowed,  or  retained  in  the  system  from  tissue  waste,  as 


COAGULATION   OF  BLOOD 


217 


in  fevers,  or  renal  or  thyroid  disease.  Low  pressure  is  observed  in 
conditions  of  depression,  or  in  muscle  exhaustion,  or  after  exhaust- 
ing illness;  in  warm  surroundings,  etc.,  etc. 

Blood  pressure  is  easily  influenced  by  the  use  of  drugs.  For 
example,  nitro-glycerin  lowers  it  by  dilating  the  arterioles;  strych- 
nia raises  it  by  contracting  them;  these  are  familiar  examples. 
Many  more  might  be  cited. 

Hemorrhage  is  the  escape  of  blood  in  quantity,  from  an  injured 
vessel.  Arterial  hemorrhage  flows  in  a  forcible  stream,  bright  scar- 
let in  color;  if  from  a  small  vessel  it  will  be  pulsating  or  intermit- 
tent in  force;  if  from  a  vessel  of  medium  size,  the  blood  will  gush 
with  a  sudden  spurt  which  carries  to  a  rather  surprising  distance. 

Venous  hemorrhage  presents  a  steady  flow  of  darker  hue,  rapidly 
accumulating  in  a  wound. 

Capillary  hemorrhage  is  persistent  oozing. 

Coagulation  of  Blood 

Blood  which  is  exposed  to  the  air  at  the  usual  temperature  is 
seen  to  separate  into  distinct  portions — a  red,  jelly-like  mass  and  a 
transparent  straw-colored  layer  which  is  thinner.  The  dark  mass 


FIG.  149.— DIAGRAM  TO  ILLUSTRATE  THE  PROCESS  OF  COAGULATION,  i.  Fresh 
blood,  plasma  and  corpuscles.  2.  Coagulating  blood  (birth  of  fibrin).  3.  Coagu- 
lated blood  (.clot  and  serum). — (Waller.} 

is  the  coagulum,  consisting  of  fibrin  with  corpuscles  entangled  in  it. 
The  fibrin  is  essential — no  fibrin,  no  coagulation.  The  straw-col- 
ored layer  above  it  is  serum,  which  is  plasma  bereft  of  its  fibrin  and 
corpuscles  (Fig.  149).  This  same  process  may  occur  at  the  mouth 
of  a  blood-vessel  which  has  been  cut  or  ruptured,  if  the  stream 
be  not  too  forcible,  and  it  is  nature's  way  of  stopping  the  flow. 

The  serum,  or  clear,  alkaline  layer  above  the  clot,  contains  aO 
of  the  constituents  of  plasma  except  fibrin  and  corpuscles. 
The  proteins,  sugars  and  fats  in  their  various  forms,  in  combina- 


2l8  ANATOMY   AND   PHYSIOLOGY 

tion  with  substances  which  were  discarded  by  the  tissue  cells,  are 
all  represented,  dissolved  in  the  water  of  the  serum. 

It  is  serum  which  is  found  in  the  peritoneum,  pleura,  pericardium  and 
other  serous-membrane  cavities,  and  which  fills  the  raised  cuticle  when  a 
blister  "  draws."  Serum  is  the  basis  of  exudates  and  indurations.  Gases  are 
absorbed  by  serum,  carbon  dioxide  chiefly,  with  a  little  nitrogen  and  oxygen. 

Fibrin  by  itself  is  a  colorless,  sticky  protein  substance,  fibrous 
and  elastic.  It  may  be  obtained  from  freshly  drawn  blood  by 
whipping  it  with  a  glass  rod  or  more  quickly  with  small  twigs. 
(This  leaves  a  red  fluid  called  defibrinated  blood.) 

Formation  of  fibrin. — Fibrin  is  derived  from  the  fibrinogen  of 
the  blood  by  the  action  of  an  enzyme  called  thrombin. 

Source  of  thrombin. — It  is  assumed  that  something  has  hap- 
pened to  so  affect  the  leucocytes  and  blood  plates  that  they  have 
liberated  a  special  enzyme,  thrombokinase,  which  causes  the  split- 
ting off  of  thrombin  from  the  pro-thrombin  of  the  blood.  The  rest 
follows: — thrombin  acts  upon  fibrinogen,  fibrin  is  formed,  the  cor- 
puscles are  entangled,  and  coagulation  is  accomplished. 

Diagram  of  change  from  fluid  to  coagulated  blood. 

Cor-   I  Red Red  cells 

puscles  \  White  (and  platelets) .  White  cells 


Fluid 
blood 


Plasma 


Thrombokinase  I 

f  Prothrom-      Throm- 
bin  J    bin. 


Fibrinogin. 


Fibrin 


Coagu- 
lum. 


Coagu- 
lated 
blood. 


[  Serum Serum 

The  formation  of  thrombin  takes  place  only  in  the  presence  of  calcium 
salts.  (Further  than  this,  the  salts  are  not  essential  to  coagulation.) 

For  these  processes  to  go  on  it  is  necessary  that  some  unusual  condition 
be  present.  As  has  been  said,  normal  coagulation  takes  place  upon  expos- 
ure to  the  air.  In  order  that  the  blood  may  be  exposed  to  the  air,  the 
vein  or  artery  which  contains  it  must  be  wounded,  the  blood  flowing  over 
the  injured  tissues. 

So  simple  a  change  from  the  normal  condition  as  this,  is  evidently 
"unusual"  enough  to  cause  the  liberation  of  thrombokinase  from  the  leu- 
cocytes and  blood  plates  and  appearance  of  thrombin,  and  the  rougher  the 
edges  of  the  wound  or  the  more  uneven  the  surface  over  which  the  blood 
flows,  the  more  rapidly  does  coagulation  take  place. 

But  (we  are  told)  if  an  artery  or  vein  be  opened  in  a  clean  cut  with  a 
sharp  knife  and  the  blood  received  in  an  oiled  tube  under  oil  (thus  prevent- 
ing any  possibility  of  friction),  no  coagulation  follows;  while  the  same  blood 
poured  into  an  unoiled  tube  can  be  made  to  coagulate  rapidly. 


CONTROL    OF    HEMORRHAGE  2IQ 

The  time  required  for  coagulation  is  a  matter  of  some  im- 
portance from  the  clinical  standpoint.  The  average  normal  co- 
agulation time  of  undisturbed  blood  is  from  two  to  four  minutes 
for  the  beginning  of  the  process  and  seven  to  eight  for  its  com- 
pletion; these  figures  vary  under  certain  circumstances.  If  the 
blood  is  received  in  a  cool  vessel  without  disturbance,  coagulation 
takes  place  slowly,  the  corpuscles  sink  in  the  plasma,  the  red  cells 
(being  heavier)  falling  to  the  bottom  while  the  white  ones  form  a 
reddish  gray  layer  immediately  above,  or  a  "buffy  coat"  as  it  is 
called,  so  that  the  clot  appears  in  layers.  Blood  from  inflamed 
tissues  coagulates  after  this  manner. 

Does  blood  ever  coagulate  without  exposure  to  the  air;  that  is, 
within  the  vessels  of  the  living  body?  Yes,  in  certain  abnormal 
conditions.  If  the  lining  of  the  vessel  wall  is  diseased  or  rough- 
ened, or  injured — as  by  application  of  ligatures,  or  in  the  presence 
of  bacteria,  or  when  a  foreign  body  is  floating  in  the  blood  stream, 
—these  all  favor  coagulation  within  the  vessels.  High  body 
temperature  and  various  chemical  substances  have  a  similar  effect, 
—the  presence  of  oxygen  as  well,  or  the  admission  of  air. 

If  air  finds  it  way  into  a  vessel  forming  an  air  embolus,  there  is  danger  that 
it  will  induce  coagulation  upon  reaching  the  uneven  surfaces  of  the  heart  if 
not  before.  This  is  an  unusual  accident,  but  a  possible  one,  consequently 
great  care  should  be  exercised  when  filling  and  using  a  hypodermic  syringe. 
(The  double  accident  of  piercing  a  vein  and  injecting  air  would  have  to  occur 
in  order  to  do  harm  of  this  sort.) 

Arterial  blood  coagulates  more  easily  than  venous.  A  stationary  clot  within 
a  vessel  is  a  thrombus;  a  moving  clot  is  an  embolus.  A  portion  of  a  thrombus 
may  be  swept  off  in  the  stream  as  an  embolus  and,  lodging  at  some  distant 
point,  will  become  a  thrombus  there. 

Clinical  note. — Phlebitis  is  inflammation  of  a  vein.  The  blood  within 
the  vein  coagulates,  and  the  vein  feels  like  a  hard  cord. 

Coagulation  does  not  occur  in  the  blood  of  the  capillaries  nor 
within  perfectly  normal  vessel  walls  in  health,  nor  in  blood  with  a 
deficiency  of  calcium  salts. 

A  clot  within  a  blood-vessel  resembles  the  true  coagulum  but  is  not 
identical  with  it,  being  largely  composed  of  platelets  with  fewer  threads  of 
fibrin.  The  white  clot  found  in  the  heart  at  autopsy  is  mostly  fibrin. 

Control  of  hemorrhage. — Nature's  way  is  by  coagulation  at 
the  mouth  of  the  vessel.  To  favor  this,  we  seek  to  i.  slow  the 
current:  by  rest,  by  elevation  of  the  bleeding  part,  by  compression 


220  ANATOMY  AND  PHYSIOLOGY 

of  the  artery  from  which  the  blood  comes  (as  a  tourniquet  applied 
above  the  wound),  by  compress  and  bandage  over  the  wound.  2. 
To  cause  contraction  of  the  vessels:  by  applying  heat — hot  water 
118  to  1 20 — in  a  rapid  stream  if  available,  otherwise  in  hot  com- 
presses, or  cold — ice  is  best;  by  the  use  of  adrenalin,  and  possibly 
by  styptic  solutions  which  cause  a  coagulum  by  chemical  action. 
(Among  domestic  remedies,  vinegar  has  a  reputation.) 

For  internal  hemorrhage,  if  of  the  head  or  upper  part  of  the  body 
elevate  head  and  shoulders  moderately,  command  rest.  If  in 
the  pelvis  or  lower  part  of  the  body,  elevate  the  foot  of  the  bed, 
protect  from  excitement,  secure  rest.  If  from  the  lungs,  elevate 
shoulders,  forbid  speaking. 

In  case  of  sudden  and  profuse  bleeding,  when  the  vessels  are 
rapidly  emptying  themselves,  bandage  limbs  to  secure  tension 
by  driving  the  blood  into  a  smaller  area,  and  to  lessen  the  demand 
upon  the  heart;  prepare  for  hypodermoclysis,  saline  transfusion 
or  blood  transfusion. 

Since  capillary  blood  does  not  coagulate  direct  pressure  and 
time  are  required  for  the  control  of  capillary  hemorrhage. 

Opsonins  and  the  opsonic  index. — It  is  believed  that  the  phago- 
cytic  action  of  white  cells  is  regulated  by  the  presence  in  the  blood 
of  chemical  substances  (still  undescribed)  called  opsonins,  by 
which  invading  bacteria  are  prepared  for  absorption  and  digestion 
by  the  phagocytes.  The  measure  of  the  power  thus  residing  in  the 
blood  is  expressed  as  the  opsonic  index.  The  opsonic  index  is  high 
or  low,  according  to  the  number  of  bacteria  which  the  opsonins 
may  assist  the  cells  to  dispose  of. 

There  is  some  reason  for  thinking  that  a  special  opsonin  exists 
for  each  kind  of  bacterium. 

In  addition  to  opsonins  the  blood  contains  enzymes,  also 
various  antibodies  and  immune  bodies,  which  either  protect  the 
body  from  specific  infections,  or  assist  in  overcoming  invasions 
which  have  already  occurred  (see  p.  214).  Each  separate  poison 
or  bacterium  has  its  own  antibody.  The  so-called  internal 
secretions  are  also  carried  by  the  blood  (p.  263). 


CHAPTER  XIII 
THE  LYMPH  SYSTEM.     LYMPH  CIRCULATION 

The  lymphatic  system  comprises  an  extensive  arrangement  of 
lymph  vessels  or  lymphatics,  and  lymph  nodes  (or  glands} — both  deep 
and  superficial  (Fig.  150). 

This  system  pervades  the  entire  body  for  the  circulation  of 
lymph — a  nutritive  fluid  derived  from  the  blood.  It  is  by  this 
means  that  foods  which  have  been  absorbed  from  the  digestive 
organs  and  poured  into  the  blood  are  separated  out  for  the  use  of 
the  tissues  and  conveyed  to  them. 

Lymph  spaces. — Between  the  cells  and  collections  of  cells  of 
every  tissue,  except  cuticle,  hair  and  nails,  are  found  minute  tissue 
spaces  or  lymph  spaces,  communicating  freely  with  each  other. 
There  are  also  spaces  around  the  smallest  blood-vessels  and  nerves 
(called  respectively  perivascular  and  perineural  spaces) .  These  all 
communicate  with  the  beginnings  of  lymph-capillaries  (just  how, 
is  disputed). 

Lymph  capillaries. — These  resemble  blood  capillaries  in  that 
they  have  but  a  single  coat  (of  endothelium).  They  permeate  the 
tissues  in  every  direction,  forming  a  close  network,  from  which 
lymph  vessels  or  lymphatics  originate  by  the  uniting  of  small 
channels  to  form  larger  ones  (as  veins  originate) . 

Lymph  vessels. — Are  delicate  and  transparent,  but  have  three 
flexible  coats.  (One  elastic,  two  nbro-muscular.)  They  are  pro- 
vided with  valves,  formed  by  folds  of  the  lining  at  very  short  inter- 
vals, which  give  the  appearance  of  beading  to  the  vessels.  This 
arrangement  allows  the  lymph  to  flow  toward  the  heart  but  pre- 
vents it  from  moving  in  the  other  direction. 

The  lymph  vessels  of  the  intestines  have  been  called  lacteals 
because  of  their  milky  appearance  during  the  process  of  digestion, 
the  whitish  color  being  due  to  the  presence  of  fat  globules  trans- 
mitted by  the  lymph  capillaries  of  the  villi.  This  fat-bearing 
lymph  is  called  chyle. 

221 


222 


ANATOMY   AND   PHYSIOLOGY 


Within  the  tissues  of  the  body  the  lymph  vessels  are  too  small 
to  be  seen  by  the  naked  eye,  but  they  unite  again  and  again  to 
form  larger  ones  (although  still  very  small)  which  in  some  places 
may  be  seen  entering  or  leaving  glands,  until  finally  two  remain — 
the  right  lymphatic  duct  and  the  thoracic  duct,  which  have  a  diameter 
of  3  or  4  mm. 


FIG.  150. — LYMPHATIC  VESSELS  AND  NODES. 
i  and  2  are  portions  of  the  THORACIC  DUCT. — (Sappey.} 

Lymph  is  a  transparent  watery  saline  fluid  with  lymph  cor- 
puscles floating  therein.  It  contains  nutritive  substances  for  the 
tissues  and  waste  matters  derived  from  them. 

The  description  of  plasma  applies  very  well  to  lymph,  always  keeping  in 
mind  that  lymph  is  more  watery  and  carries  lymph  cells  while  plasma  bears 
blood  cells;  lymph  coagulates  but  slowly  and  not  so  firmly,  with  a  pale  clot 
because  of  the  absence  of  red  cells. 

The  origin  of  lymph  is  primarily  from  the  blood.  The  walls  of 
the  blood-capillaries  allow  a  transudation  of  thin  plasma  or  serum 


THORACIC    DUCT  223 

into  the  tissue  spaces,  and  this  is  the  source  of  its  nutritive  principles. 
Waste  matters  are  added  as  the  result  of  the  activities  of  the  tissues 
themselves;  they  represent  the  "tissue  waste"  This  fluid,  con- 
veyed by  lymph-capillaries  to  lymph-vessels,  is  carried  to  lymph 
glands,  where  it  gathers  the  lymph  corpuscles  which  float  in  it. 

Lymph  nodes  or  lymph  glands  are  small  round  or  oval  bodies 
of  a  reddish  color,  varying  in  size  from  that  of  a  pin  head  to  a 
small  bean,  and  intersecting  the  lymph  vessels  in  certain  regions  of 
the  body.  They  are  numerous  in  the  neck,  axilla  and  groin,  also 
in  the  thorax  and  abdomen. 

A  lymph  gland  is  invested  with  a  thin  but  firm  capsule  (fibro- 
muscular)  which  sends  septa  or  partitions  into  the  interior,  to 
support  the  gland  substance  in  small  compartments.  The  gland 
(lymphoid  or  adenoid}  substance  lies  loosely  in  this  capsule  and  in 
the  compartments,  leaving  spaces  for  the  passage  of  lymph  around 
the  different  portions  and  around  the  whole.  It  contains  great 
numbers  of  young  corpuscles,  which  are  added  to  the  lymph  stream 
as  it  washes  through  the  gland,  and  appear  later  as  the  lymphocytes 
of  the  blood. 

Lymph  is  brought  to  the  glands  by  afferent  lymph  vessels, 
usually  several  for  each  gland.  After  flowing  through  the  various 
spaces  in  and  around  the  gland  substance,  it  leaves  by  efferent 
vessels,  which  unite  to  carry  the  stream  on  its  way  toward  the 
large  veins. 

A  specimen  taken  from  an  e/erent  vessel  and  examined  under  the  micro- 
scope will  show  a  greater  number  of  lymphocytes  than  one  taken  from  an 
afferent  vessel. 

The  largest  lymph  vessel  is  called  the  thoracic  duct  (p.  189). 
It  is  about  1 8  inches  long,  having  an  average  diameter  of  a  small 
goose-quill.  It  begins  at  the  second  lumbar  vertebra,  in  a  little 
pouch  called  the  receptacle  of  the  chyle  (or  receptaculum  chyli)  and 
runs  up  behind  the  aorta,  through  the  diaphragm.  It  then  con- 
tinues upward  through  the  thorax  to  the  level  of  the  seventh  cer- 
vical vertebra,  where  it  arches  over  to  open  into  the  left  sub- 
clavian  vein  (at  the  junction  with  the  left  internal  jugular).  Thus 
the  lymph  and  chyle  join  the  current  of  venous  blood  on  its  way  to 
the  heart  for  circulation  and  distribution. 

The  right  lymphatic  duct  is  a  short  vessel,  a  half  inch  in 
length,  which  opens  into  the  right  subclavian  vein  at  the  junction 


224  ANATOMY  AND   PHYSIOLOGY 

with  the  right  internal  jugular.  Through  this  channel  lymph 
alone  joins  the  venous  blood  on  its  way  to  the  heart. 

Note. — The  cavities  of  serous  membranes,  as  peritoneum, 
pleura,  pericardium  and  others,  belong  to  the  system  of  lymph- 
spaces,  but  of  a  special  kind.  They  are  surrounded  by  capillaries 
which  communicate  with  them  by  tiny  openings  in  the  membrane, 
called  stomata. 

Like  the  venous  blood  current,  lymph  flows  toward  the  heart. 
After  the  lymph  vessels  are  formed  and  receive  their  contents 
from  the  tissues,  they  take  a  fairly  independent  course.  The 
larger  glands  are  found  in  the  neighborhood  of  veins  as  a  general 
rule  but  not  in  the  same  sheath;  knowing  the  situation  of  the 
glands  and  bearing  in  mind  that  the  actual  lymph  stream  flows 
from  the  tissues  toward  the  heart,  their  course  is  easily  traced  and 
is  of  interest  and  importance  as  a  swollen  lymph  node  gives  a  clue 
to  the  possible  location  of  the  cause. 

SITUATION  OF  THE  PRINCIPAL  GROUPS  OF  NODES 
OR  GLANDS 

BELOW  THE  DIAPHRAGM 

Lower  extremity. — Popliteal,  in  the  popliteal  space,  inguinal 
(important)  at  the  oval  fossa  and  along  the  inguinal  ligament 
(Fig.  152). 

Pelvis:  External  and  internal  iliac,  with  the  external  and 
internal  iliac  vessels. 

Abdomen:  Mesenteric,  between  the  layers  of  the  mesentery 
(about  150);  lumbar,  in  front  of  the  aorta  and  vena  cava.  These 
are  numerous. 

ABOVE  THE  DIAPHRAGM 

Upper  extremity. — Epitrochlear ,  above  the  internal  epicondyle; 
axillary,  under  the  axillary  walls,  and  clavicular,  along  the  sub- 
clavian  vessels  (Fig.  150). 

The  axillary  glands  are  superficial,  under  the  borders  of  the  muscle 
boundaries;  and  deep  around  the  axillary  vessels.  These  are  very  important. 

Head:  Occipital,  below  the  occiput;  auricular,  behind  the  ear; 
parotid,  upon  the  parotid  gland;  submaxillary ,  under  the  angle  of 
the  jaw  (Fig.  150). 


NODES    OR    GLANDS 


225 


Lymph-nodes 


Small  saphena 
vein 


Lymph- 
nodes 


Lymph- 
nodes 


FIG.  1 5 1 . — THE  LYMPHATICS  AND 
LYMPH-NODES  OF  THE  LOWER  EX- 
TREMITY, POSTERIOR. 


FIG.  152. — THE  LYMPHATICS  AND 
LYMPH-NODES  OF  THE  LOWER  Ex~ 
TREMITY,  ANTERIOR. 


226  ANATOMY   AND    PHYSIOLOGY 

Neck:  Superficial  cervical,  near  the  external  jugular  vein; 
deep  cervical,  with  the  large  vessels  (carotid  arteries  and  internal 
jugular  vein.)  (Important.) 

Thorax:  Mediastinal,  with  the  vessels  in  the  mediastinum;1 
bronchial,  with  bronchial  tubes  and  vessels — these  are  numerous. 


Lacteals 


Veins 


FIG.  153.—! LACTEALS  AND  MESENTERIC  GLANDS. — (Morris.} 


COURSE  OF  THE  LYMPH  STREAM 

BELOW  THE  DIAPHRAGM 

Knowing  the  location  of  the  glands,  and  remembering  that  lymph  flows 
toward  the  heart,  the  course  of  the  stream  is  easily  understood. 

From  the  lower  extremity  up  through  popliteal,  saphenous,  and  inguinal 
glands  to  the  external  iliac,  and  thence  to  the  lumbar  glands. 

From  the  buttock  and  anterior  parts  of  the  genital  organs  to  the  inguinal, 
external  iliac,  and  thence  to  the  lumbar  glands. 

In  the  deeper  parts  of  the  genital  organs  to  the  internal  iliac,  and  thence 
to  the  lumbar  glands. 

From  the  pelvic  organs  or  viscera  to  the  internal  iliac,  and  thence  to  lumbar 
glands. 

The  ovaries,  tubes,  and  fundus  of  the  uterus  send  their  lymph  directly  to 
the  lumbar  glands,  instead  of  first  through  the  internal  iliac. 

From  the  abdomen,  lymph  from  the  abdominal  walls  flows  to  lumbar 
glands  (sometimes  indirectly),  also  from  the  kidneys  and  adrenals  to  the 
lumbar  glands. 

1  See  page  365,  The  mediastinum. 


LYMPHATICS    OF    THE    MAMMARY    GLAND 


227 


From  intestines  through  mesenteric  glands  to  the  thoracic  duct;  from  all 
remaining  abdominal  organs  to  the  thoracic  duct  (except  upper  surface  of 
the  liver). 

All  lymph  which  flows  through  lum- 
bar glands  runs  to  the  thoracic  duct,  and 
through  it  to  the  left  subdavian  vein. 

Note. — The  lymphatics  in  the  mesen- 
tery, coming  from  the  small  intestine, 
convey  not  only  lymph  but  chyle  also, 
which  is  light  in  color  and  gives  to  them  a 
milky  appearance,  therefore  their  name, 
lacteals  (Fig.  153). 

ABOVE  THE  DIAPHRAGM,  LEFT  SIDE 

From  the  left  upper  extremity  through 
axillary  and  subdavian  glands  to  the  deep 
cervical  glands,  thence  to  thoracic  duct. 

From  left  head  and  neck,  superficial : 
face  and  scalp,  to  occipital,  submaxillary, 
superficial  cervical,  and  then  deep  cervical 
glands.  Deep :  face,  throat  and  neck,  to 
deep  cervical  glands  and  thence  to  thoracic 
duct. 

From  the  left  thorax,  walls  and  vis- 
cera (including  left  half  of  heart),  to 
thoracic  duct. 

ABOVE  THE  DIAPHRAGM,  RIGHT 
SIDE 

From     the    right    upper    extremity 

through  axillary,  subdavian,  and  deep 
cervical  glands,  to  the  right  lymphatic  duct 
(p.  228). 

From  the  right  head  and  neck  through 
occipital,  submaxillary,  superficial  and  deep 
cervical  glands,  to  right  lymphatic  duct. 

From  the  right  thorax,  walls  and  vis- 
cera (including  right  half  of  heart),  to 
right  lymphatic  duct. 

Lymphatics   of  the  mammary 

gland. — Most  of  these    empty  into   FlG-  i54-— LYMPHATICS  AND  NODES 

_   .  OF  UPPER  EXTREMITY. 

superficial  and  deep  axillary  glands; 

a  few  pass  through  the  chest  wall  to  mediastinal  glands;  those 


228  ANATOMY   AND   PHYSIOLOGY 

of  the  nipple  and  areola  of  the  two  sides  communicate  with  each 
other. 

SUMMARY  AND  FUNCTIONS 

The  right  lymphatic  duct  gathers  lymph  from  the  right  upper 
extremity,  right  head,  neck,  thorax  and  thoracic  viscera,  and  the 
upper  surface  of  the  liver. 

The  thoracic  duct  gathers  lymph  from  all  other  parts  of  the 
body — that  is,  the  left  side  above  the  diaphragm,  and  all  parts 
below  the  diaphragm,  except  the  upper  surface  of  the  liver.  The 
two  ducts  empty  into  the  two  subclavian  veins,  and  thus  the  lymph 
joins  the  blood  current. 

The  Flow  of  the  Lymph  Stream. — This  is  maintained  by  the 
same  forces  which  are  concerned  in  the  flow  of  blood  in  the  veins — 
(i)  the  aspiration  of  the  thorax;  (2)  the  intermittent  pressure  and 
relaxation  of  surrounding  muscles  throughout  the  body;  (3)  the 
constantly  lowering  resistance  in  front  of  the  stream  as  the  vessels 
grow  larger;  (4)  probably  by  the  action  of  muscle-fibers  in  the  walls 
of  lymph  vessels  and  the  assistance  of  the  numerous  valves,  by 
which  they  hold  what  they  receive,  never  allowing  the  stream  to 
fall  back.  Add  to  these  general  forces  the  special  influence  of 
the  peristaltic  movements  of  the  alimentary  tract;  these  must 
cause  a  rhythmic  closing  and  opening  of  the  lymph  vessels  which 
are  the  most  active  of  any  in  the  body,  and  in  consequence,  a  large 
volume  of  lymph  containing  the  products  of  digestion,  is  set  in 
motion. 

Clinical  notes. — Certain  conditions  of  disease  in  an  organ  or  tissue  are 
followed  by  enlargement  of  the  nearest  glands  which  receive  lymph  from  that 
part.  If  the  disease  be  not  arrested,  the  glands  next  in  order  will  suffer,  and 
the  next,  and  the  next. 

Disease  of  the  mammary  gland  will  cause  swelling,  first,  of  the  superficial 
glands  under  the  border  of  the  pectoral  muscle,  and  later  of  the  deep  axillary 
and  clavicular  glands.  Mediastinal  glands  are  sometimes  affected  when  the 
upper  portion  of  the  gland  is  diseased. 

Disease  of  the  tonsils  will  affect  the  submaxillary  and  cervical  glands. 

Disease  of  the  pharynx,  the  cervical  glands. 

Disease  of  the  larynx  will  affect  the  cervical  glands,  and  may  affect  the 
mediastinal  and  bronchial  glands. 

Disease  of  the  upper  extremity  will  cause  swelling  of  the  axillary  glands. 

Disease  of  the  lower  extremity  will  affect  the  saphenous  group  and  the 
inguinal. 


EDEMA  EFFUSION  229 

Disease  of  the  external  genital  organs  and  lower  end  of  vagina  will  affect  the 
inguinal  glands  along  the  inguinal  ligament. 

Disease  of  the  neck  of  the  womb  (cervix  uteri)  will  affect  iliac  glands, 
while  disease  of  the  body  of  the  womb  (fundus  uteri),  or  of  ovaries  or  tubes, 
will  affect  lumbar  glands. 

The  transmission  of  the  causes  of  disease  from  one  organ  to  another  by  the 
lymphatics  is  called  metastasis;  it  is  often  seen  to  follow  a  malignant  growth. 

The  lymph  itself,  as  we  have  seen,  is  the  medium  between  the 
blood  and  the  tissues.  It  is  only  through  the  lymph  that  the  blood 
can  feed  the  tissues  and  receive  the  products  of  their  metabolism. 
The  thinness  of  the  capillary  wall  allows  this  interchange  between 
blood  plasma  and  the  lymph  in  the  spaces  around  the  vessels. 
The  one  place  of  exception  is  in  the  lungs.  There,  oxygen  from 
the  air  passes  directly  into  the  capillary  blood  and  Co2  from  the 
blood,  directly  into  the  air  of  the  lungs. 

The  process  of  osmosis  has  already  been  mentioned,  in  con- 
nection with  food  absorption  and  in  considering  the  physiology 
of  the  blood  (pages  170  and  214).  It  is  by  the  forces  included 
under  this  name  that  the  nutritive  substances  circulating  in  the 
blood  are  delivered  to  the  tissues  and  wastes  are  at  the  same 
time  removed  from  them. 

Clinical  notes. — Edema  is  an  accumulation  of  lymph  in  the  tissue  spaces. 
We  have  seen  that  an  interchange  between  the  blood  and  lymph  capillaries  is 
continually  going  on,  the  blood  providing  lymph,  the  tissues  receiving  it, 
abstracting  nutriment  and  adding  waste.  This  is  not  all  returned  to  the 
capillaries,  a  portion  is  left  in  the  spaces  to  be  carried  by  lymph  vessels  to 
the  two  lymph  ducts  which  convey  it  to  certain  large  veins. 

Should  this  balance  of  interchange  be  disturbed,  the  effect  is  evident  at 
once.  Whether  the  supply  be  too  abundant  or  the  outflow  be  obstructed 
the  same  result  would  follow — the  tissues  would  be  overwhelmed  with 
fluid,  causing  edema. 

Inflammation  of  serous  membranes,  if  severe,  results  in  the  accumulation 
of  lymph  or  serum  in  their  cavities — this  is  an  effusion. 

Inflammation  in  the  tissues  themselves  causes  a  local  excess  of  lymph 
derived  from  the  increased  quantity  of  blood  or  hyperemia,  induced  by  local 
irritation.  The  accumulation  of  excess  lymph  constitutes  induration  or 
hardening. 

Hyperemia  is  evident  to  the  eye  when  near  the  surface,  by 
the  redness  and  heat  which  it  causes.  The  vessels  become  so 
crowded  with  cells  that  the  blood  can  move  with  difficulty.  Serum 
and  corpuscles  make  their  way  through  the  vessel  walls  and  fill 


230  ANATOMY   AND    PHYSIOLOGY 

the  lymph  spaces,  which  are  still  more  crowded  by  the  lymph  with 
its  corpuscles  held  back  in  the  hardened  tissues.  If  the  invading 
microorganisms  which  have  set  up  all  the  trouble  are  not  too 
numerous,  the  phagocytes  aided  by  opsonins  will  dispose  of  them. 
Then  they  and  the  entire  accumulation  in  the  tissues — remnants  of 
cells  and  bacteria,  fluids,  etc.,  will  be  removed  by  way  of  the  regu- 
lar lymph  channels  as  the  swelling  subsides. 

Clinical  note. — The  nurse  becomes  very  familiar  with  the  treatment  of 
this  condition  of  induration;  for  example — by  the  use  of  hot  douches  to 
assist  the  removal  of  a  pelvic  "exudate"  by  improving  the  circulation  in 
the  region  and  in  this  way  favoring  absorption.  (A  pelvic  exudate  is  usually 
situated  in  the  broad  ligaments  of  the  uterus.) 

SUMMARY  OF  FUNCTIONS  OF  THE  LYMPH  SYSTEM 

By  the  lymph,  to  present  to  the  tissues  their  proper  nutriment 
and  to  receive  the  waste  products  of  their  metabolism. 

By  the  lymph  spaces,  to  transmit  the  nutritive  fluid  from  the 
blood  to  the  tissues,  and  waste  matters  from  the  tissues  to  the  blood. 

By  lymph  capillaries  and  vessels,  to  convey  lymph  to  the  blood 
in  the  large  veins. 

By  lymph  nodes  or  glands,  to  give  origin  to  lymphocytes,  and  to 
filter  out  and  retain  poisonous  or  injurious  substances  from  the 
lymph  stream. 


CHAPTER  XIV 

PULMONARY  RESPIRATION  AND  RESPIRATORY 

ORGANS 

Respiration  is  the  term  used  to  express  the  interchange  of  gases 
between  the  blood  and  the  surrounding  tissues,  the  gases  being 
oxygen  and  carbon  dioxide. 

Pulmonary  respiration  takes  place  in  the  capillary  system  of  the 
lungs.  The  interchange  is  between  the  blood  and  the  atmosphere, 
or  external  air;  hence,  the  process  in  the  lungs  is  called  external 
respiration. 

The  exchange  which  takes  place  in  the  capillaries  of  the  tissues 
elsewhere  is,  on  the  other  hand,  called  internal  respiration.  As  this 
depends  entirely  upon  the  intake  of  oxygen  by  the  lungs  and  the 
removal  of  carbon  dioxide  in  the  same  organs,  the  use  of  the  word 
respiration  without  qualifying,  has  come  to  signify  pulmonary  or 
external  respiration,  commonly  termed  breathing. 

Inspiration  is  the  act  of  drawing  air  into  the  lungs;  expira- 
tion is  the  act  of  expelling  it.  An  inspiration  and  an  expiration 
together  constitute  a  pulmonary  respiration. 

By  air  is  meant  the  atmospheric  air  by  which  we  are  surrounded. 
It  consists  principally  of  the  two  gases,  oxygen  and  nitrogen,  one 
hundred  parts  by  weight  of  air  containing  a  little  more  than  twenty 
of  oxygen  and  a  little  less  than  eighty  of  nitrogen,  or,  in  the  pro- 
portion of  one  of  O  to  four  of  N,  roughly  speaking.  It  is  the 
oxygen  which  is  the  essential  part  of  inspired  air. 

The  respiratory  organs  are  the  nose,  pharynx,  larynx,  trachea, 
bronchial  tubes,  and  lungs,  with  the  thorax  and  its  muscles,  in- 
cluding the  diaphragm;  and  the  pulmonary  blood-vessels.  These 
organs  constitute  the  respiratory  apparatus  and  they  include  the 
respiratory  tract,  which  is  a  series  of  channels  or  air-passages  at 
the  termination  of  which  the  air  comes  into  contact  with  the 
respiratory  epithelium. 

The  nose. — -The  external  nose  is  a  framework  of  bone,  cartilage 
and  skin.  The  dorsum  is  formed  by  the  meeting  of  the  lateral 

231 


232 


ANATOMY  AND   PHYSIOLOGY 


surfaces  in  the  median  line.  Each  lateral  surface  terminates  below 
in  the  wing  of  the  nose — ala  nasi.  The  alae  are  flexible  and  move- 
able.  The  part  that  is  supported  by  the  nasal  bones  is  the  bridge 
of  the  nose.  The  nostrils  are  the  expanded  portion;  they  contain 
no  bones,  but  small  plates  of  cartilage  instead,  which  are  moved  by 
little  muscles,  therefore,  they  may  be  expanded  or  contracted. 

Immediately  within  the  margins  of  the  nostrils  are  the  vestibules;  each 
vestibule  terminates  within  the  tip  of  the  nose  in  a  small  pouch,  the  ventricle. 
The  nostrils  and  vestibules  of  the  right  and  left  sides  are  separated  by  thin 
cartilages  forming  a  mobile  septum  (columna). 


JJ 

FIG.  155 — .NASAL  CAVITY  ANDN  ASO-PHARYNX. — (From  Dealer's  Surgical  Anatomy.} 
b,  Superior  turbinal;  a,  superior  meatus;  c,  middle  turbinal;  s,  middle  meatus;  d, 
inferior  turbinal;  «,  inferior  meatus;  g,  i,j,  tongue;  k,  hyoid  bone;  p,  q,  r,  sphenoid 
bone  and  sphenoidal  sinus;  t,  naso-pharynx;  v,  hard  palate  (floor  of  nose). 
The  remaining  references  are  explained  in  another  chapter  (p.  136). 

Their  internal  margins  are  provided  with  stiff  hairs  to  arrest 
particles  of  foreign  substance  in  the  inspired  air. 

The  cavity  of  the  nose  is  divided  into  the  right  andjeft  cavities 


THE    LARYNX  233 

or  fossa  by  a  partition  called  the  septum,  the  anterior  portion  of 
the  septum  being  formed  by  the  triangular  cartilage  of  the  nose, 
the  remaining  portion  by  bones  —  the  vomer  and  the  vertical 
plate  of  the  ethmoid  (Fig.  26).  The  openings  upon  the  face  are 
the  nares  (anterior  nares)  and  those  at  the  back  (looking  into  the 
nasopharynx)  are  the  choance  (posterior  nares)  . 

On  the  lateral  wall  of  each  nasal  cavity  are  three  turbinated 
bones  or  shells  (conchae),  and  three  spaces  or  passages  directly 
underneath  them,  named  as  follows:  the  superior  meatus  (or 
passage)  beneath  the  superior  concha  (or  shell)  ;  the  middle  meatus 
beneath  the  middle  concha;  and  the  inferior  meatus  beneath  the 
inferior  concha  (Fig.  25).  The  upper  part  of  each  fossa  is  the 
olfactory  part;  all  below  that  is  the  respiratory  part. 

Breath  is  the  air  from  the  lungs  with  all  that  it  contains;  breathing,  then, 
is  producing  air  which  has  been  passing  through  the  lungs. 

The  nasal  cavities  and  all  of  the  sinuses  which  communicate 
with  them  are  lined  with  mucous  membrane, 
which  by  the  mucus  on  its  surface,  prevents 
the  drying  effect  of  the  air  upon  the  pas- 
sages, arrests  foreign  particles,  and  moder- 
ates the  temperature  of  the  air  on  its  way 
to  the  lungs.  As  an  organ  of  respiration, 
the  nose  is  important  because  nasal  respira- 
tion moistens,  filters  and  warms  the  air  we  FIG.  156.—  CILIATED  EPI- 
breathe.  TBSLTU*.—  (Stirling. 


The  mucous  membrane  of  the  nasal  fossae  is  called  the  Schneiderian  mem- 
brane. It  is  ciliated  in  the  respiratory  part.  In  the  olfactory  part  the 
olfactory  cells  are  found,  which  receive  the  impressions  leading  to  the  sense  of 
smell.  For  the  nose  as  an  organ  of  the  sense  of  smell,  and  of  voice,  see 
pp.  326  and  345. 

THE  PHARYNX 

The  pharynx  is  the  space  behind  the  nose,  mouth,  and  larynx. 
Its  use  is  to  transmit  air  from  the  nose,  and  food  from  the  mouth. 
As  an  air-passage  it  is  included  with  the  respiratory  organs.  (The 
air  passes  from  the  nose  through  the  pharynx  to  the  larynx.) 

THE  LARYNX 

The  larynx  is  situated  below  the  hyoid  bone,  in  front  of  the 
pharynx,  and  projects  slightly  forward  in  the  neck.  It  is  con- 


234 


ANATOMY  AND   PHYSIOLOGY 


structed  of  fibre-cartilages  connected  with  each  other  by  ligaments 
and  lined  by  mucous  membrane.  The  largest  fibre-cartilage  is  the 
thyroid,  which  forms  the  prominence  of  the  larynx  known  as 
"Adam's  apple."  Below  the  thyroid  is  the  cricoid  cartilage, 
shaped  like  a  seal  ring,  and  placed  with  the  broad  part  at  the 
back,  where  two  small  pyramid-shaped 
cartilages  rest  upon  it;  they  are  the  aryte- 
noids.  These  are  all  connected  by  gliding 
joints.  (Other  cartilages,  very  minute, 
are  not  mentioned.) 

The  epiglottis  is  a  leaf-shaped  flexible 
cartilage  extending  upward  from  the  thy- 
roid in  front,  and  resting  against  the  base 
of  the  tongue.  During  swallowing  this  is 
bent  backward  over  the  entrance  of  the 
larynx  by  the  action  of  small  muscles,  to 
allow  the  food  to  pass  over  it  into  the 
esophagus.  (For  the  Larynx,  the  Organ 
of  the  Voice,  see  page  344.) 


FIG.  157. — INTERIOR  OF 
LARYNX  (LEFT  SIDE  RE- 
MOVED) . — (Sappey) . 

2,  Epiglottis;  5,  so-called 
"false  vocal  cord";  9,  vocal 
band;  13,  thyroid  cartilage; 
14,  arytenoid  cartilage. 
The  other  figures  refer  to 
parts  not  mentioned  in  the 
text. 


THE  TRACHEA 


The  trachea  is  a  flexible  tube  about 
one -inch  in  diameter  and  four  and  one- 
half  inches  long,  extending  downward  from  the  larynx  to  the 
level  of  the  fourth  thoracic  vertebra.  It  is  fibrous  and  elastic, 
and  stiffened  with  rings  of  cartilage  which  are  incomplete  at  the 
back;  unstriped  muscle  fibers  take  their  place,  constituting  the 
tracheal  muscle. 

The  tracheal  muscle  makes  the  tube  soft  where  the  esophagus  lies  next  to 
it,_and  by  the  action  of  its  fibers  varies  the  size  of  the  trachea. 

The  trachea  divides  into  two  branches  called  bronchi.  The 
right  bronchus  is  one  inch  long;  the  left  is  two  inches  long  (it 
passes  under  the  arch  of  the  aorta) . 

The  bronchi  divide  into  branches  called  bronchial  tubes  which 
subdivide  again  and  again  until  the  smallest  tubes,  called  bron- 
chioles, are  formed.  These  lead  to  the  spaces  called  alveoli,  and 
the  air  cells  clustered  about  them. 


THE    LUNGS 


235 


The  bronchi  and  larger  bronchial  tubes  are  like  the  trachea  in  structure, 
consisting  of  fibrous  and  elastic  tissue  with  incomplete  rings  of  cartilage.  In 
the  smaller  tubes  the  rings  become  irregular  plates  or  discs,  and  in  the  bron- 
chioles the  cartilage  is  absent  altogether.  The  walls  are  here  very  thin  and 
contain  circular  muscle  fibers  (non-striated),  the  bronchial  muscle. 

The  entire  tract  from  the  trachea  down  to  the  air  cells  is  lined 
with  mucous  membrane,  bearing  ciliated  epithelium  (Fig.  156)  as 
far  as  the  smallest  tubes. 


Thyroid  cartilage 


Cricoid  cartilage 


Left  bronchus 


FIG.  158. — LARYNX,  TRACHEA,  AND  BRONCHI. — (Morris,  modified  from  Bourgery.) 

p   The  cilia  of  the  air  passages  are  fine  hair-like  projections  from  the  surface; 
they  have  a  waving  motion,  exerted  forcibly  in  a  downward  direction. 


THE  LUNGS 

The  lungs  are  two  in  number,  right  and  left,  situated  in  the 
right  and  left  sides  of  the  thorax,  occupying  the  space  enclosed 
by  the  ribs  (not  that  portion  between  the  sternum  and  the  spinal 
column).  They  resemble  a  flattened  cone  in  shape,  the  apex 


236 


ANATOMY   AND    PHYSIOLOGY 


extending  one  inch  above  the  clavicle,  the  base  resting  upon  the 
diaphragm.     The  right  lung  is  broader  and  shorter  than  the  other, 

but  it  has  three  lobes,  upper,  middle,  and 
lower.     The  left  lung  has  two  lobes. 

Note. — The  left  lung  is  narrower 
than  the  right  and  does  not  cover  the 
apex  of  the  heart,  otherwise  it  would  be 
exposed  to  the  motion  of  the  "heart 
beat." 

The  lung  substance  consists  of 
branches  of  the  bronchi  and  their  divi- 
sions down  to  the  bronchioles,  and  the 
spaces  terminating  in  air-cells.  These 
structures  are  surrounded  by  blood- 
vessels, nerves,  and  lymphatics,  grouped 
together  in  lobules,  supported  by  fine 


FIG.  159. — CLUSTERS  OF 
AIR-CELLS. — (Hoi den,  from 
Kolliker.) 


fibre-elastic  tissue  and  wrapped  in  pleura. 

Each  bronchiole  terminates  in  a  lobule. 

The  root  of  the  lung 
is  composed  of  the  large 
bronchial  tubes,  blood- 
vessels, and  nerves  (Fig. 
160). 

The  bronchial  tubes  are 
the  primary  divisions  of  the 
bronchi;  the  blood-vessels 
are — first,  the  bronchial  ar- 
teries for  the  nutrition  of  the 
lung  substance;  second,  the 
pulmonary  arteries  which 
form  a  fine  network  of  capil- 
laries around  the  air-cells, 
third,  the  bronchial  and  pul- 
monary veins.  They  enter 
and  leave  the  lung  at  the 
hilum — a  depression  on  the 
medial  surface. 


FIG.  1 60. — THE  LUNGS  WITH  HEART 
BETWEEN  THEM. 


THE  PLEURAE 

Each  lung  is  covered  (except  at  the  root)  by  a  thin  transparent 
sac  of  serous  membrane  called  the  pleura.     One  side  of  this  sac  is 


THE    PLEURA  237 

closely  applied  to  the  lung,  forming  the  pulmonary  pleura;  the  other 
side  fits  as  closely  to  the  ribs,  forming  the  costal  pleura.  Within 
the  sac  is  a  small  quantity  of  serous  fluid  (secreted  by  the  endothe- 
lium  of  the  pleura),  which  prevents  friction  when  the  ribs  move 
and  the  lungs  expand  or  contract. 

Although  the  bony  thorax  is  bounded  above  by  the  first  rib, 
the  thoracic  cavity  extends  an  inch  above  the  rib  on  each  side, 
bounded  by  an  expansion  of  the  costal  pleura  and  lodging  the  apex 
of  the  lung. 

R.  mammary 
artery 

L.  phrenic  nerve 

m     ma     ^Mom^BHH     I^MI    <m 

R.  phrenic  nerve 


FIG.  161. — THE  PLEURAL  SACS. 

The  dotted  lines    indicate  the  pleural    sacs,  with    space    between    the    layers. 

(H  olden.) 

Clinical  note. — If  the  pleura  becomes  inflamed  the  quantity  of  fluid 
diminishes  and  the  surfaces  rub  together,  causing  acute  pain  and  a  fine 
crackling  sound  as  of  friction.  This  condition  is  pleuritis  or  pleurisy. 

Resume. — In  respiration,  or  the  act  of  breathing,  the  inspired 
air  enters  the  nasal  chambers,  passes  through  the  naso-pharynx, 
oro-pharynx,  larynx,  trachea,  bronchi,  bronchial  tubes,  and  bron- 
.  chicles,  to  the  alveoli  and  air-cells  or  air  vesicles. 

THE  PHYSIOLOGY  OF  THE  RESPIRATORY  PROCESS 

The  function  of  the  respiratory  apparatus  is  first,  to  accom- 
plish an  interchange  in  the  lungs  between  the  oxygen  of  the  air 
and  carbon  dioxide  of  the  blood,  in  other  words — to  bring  nutri- 
ment to  the  blood  and  to  remove  waste  from  it. 


238  ANATOMY   AND   PHYSIOLOGY 

We  have  seen  how  the  blood  returns  from  the  digestive  organs 
laden  with  food  which  is  to  be  distributed  throughout  the  body, 
where  the  products  of  digestion  are  made  over  in  the  tissues  by  a 
series  of  changes  in  which  oxygen  plays  an  essential  part.  The 
source  of  the  oxygen  for  this  purpose  is  the  air  we  breathe.  It 
passes  through  the  air  vesicles  and  the  capillary  walls  into  the 
blood,  thence  into  the  lymph  spaces  and  tissue  cells. 

The  gas  called  carbon  dioxide  (resulting  from  tissue  action) 
is  brought  by  the  blood  to  the  lungs;  passing  through  the  capillary 
walls  and  the  air  vesicles,  it  is  exhaled  in  the  breath  and  thus  re- 
moved from  the  body.  Consequently,  respiration  is  a  process  not 
only  of  nutrition  but  of  elimination  as  well. 

This  interchange  is  accomplished  in  part  by  the  physical  process  of  diffu- 
sion of  gases.  (The  epithelium  of  the  air  vesicles  is  thought  to  have  a  special 
function  to  this  end,  and  is  called  respiratory  epithelium:} 

By  inspiration  we  take  air,  with  its  oxygen,  into  the  lungs;  by 
expiration  we  expel  it  with  carbon  dioxide,  small  quantities  of 
ammonia  and  organic  waste  matter,  and  moisture. 

This  important  process  is  made  possible  by  the  movements  of 
the  thorax  as  follows: 

In  inspiration. — The  external  intercostal  muscles  elevate  the 
ribs  and  spread  them  apart,  increasing  the  width  of  the  chest  ;j 
the  diaphragm  contracts,  pulling  down  its  central  tendon  and  thus 
increasing  the  depth  of  the  chest;  the  lungs  expand  and  receive  the 
in-drawn  air.  This  is  the  active  phase  of  a  respiration. 

In  expiration. — The  ribs  fall  easily  back  into  place,  assisted 
by  internal  intercostals  and  abdominal  muscles;  the  diaphragm 
relaxes,  returning  to  its  dome  shape,  and  the  air  is  pressed  out. 
This  is  the  passive  phase  of  a  respiration. 

These  acts  are  performed,  in  health,  with  regularity,  that  is, 
rhythmically.  The  number  of  respirations  in  a  moment  varies 
from  about  40  in  the  newly  born  to  18  in  the  adult.  Normal 
respiration  is  slowest  when  one  is  lying  down  or  when  sleeping. 
The  rate  is  increased  during  physical  exercise  or  by  emotion,  and 
in  visceral  inflammations,  as  pneumonia,  pleurisy,  peritonitis,  etc., 
also  in  fevers  generally. 

1  The  Pectoralis  Major  and  some  others  assist  in  deep  breathing  or  forced 
inspiration. 


RESPIRATION  239 

Average  respiratory  rate  at  different  ages: 

At  one  year 30 

"   six  years 25 

"   twelve  years 20 

Soon  after  this  age,  the  normal  proportion  between  the  number 
of  respirations  and  the  pulse  rate,  is  as  one  to  four. 

Nasal  breathing  is  the  natural  method  of  introducing  air  into 
the  respiratory  passages;  mouth  breathing  is  obstructed  breathing 
and  unnatural.  The  obstruction  is  oftenest  found  in  the  naso- 
pharynx, due  to  adenoid  growths  or  hypertrophy  of  the  naso- 
pharyngeal  tonsil.  Enlarged  tonsils  obstruct  the  oro-pharynx; 
a  deflected  septum  (p.  27)  or  hypertrophied  turbinal  bone  may 
encroach  upon  the  nasal  passages.  In  all  of  these  conditions 
mouth  breathing  is  called  to  the  aid  of  defective  nasal  breathing. 

Nasal  breathing  favors  the  development  of  the  air  sinuses  or 
resonance  chambers  which  communicate  with  the  nose.  (See 
The  Voice,  p.  344.) 

Important  note. — Mouth  breathing  leaves  the  chambers  undeveloped, 
the  voice  has  a  decidedly  nasal  quality  and,  owing  to  the  flattening  of  the 
facial  surface  of  the  maxilla  (because  the  antrum  is  small)  the  alveolar  process 
is  unduly  prominent.  (Many  bad  effects  of  mouth  breathing  might  be 
cited  if  space  and  time  were  available.) 

The  normal  respiratory  sound  has  been  well  compared  to  the 
rustling  of  leaves  when  the  gentlest  of  breezes  is  blowing  through 
them. 

The  tidal  volume  of  air  is  that  which  constitutes  a  respiration 
without  effort.  The  air  which  is  added  by  an  effort  of  inspiration 
(or  by  forced  inspiration)  is  complemental  air.  That  which  is 
expelled  by  effort  in  addition  to  a  normal  expiration,  is  reserve  air. 
A  certain  volume  always  remains  in  the  depths  of  the  cells  in  order 
to  prevent  their  entire  collapse — this  is  called  residual  air;  it  is 
changed  gradually  and  constantly. 

The  organs  concerned  in  respiration  must  be  obedient  to  a- con- 
trolling nerve  center  common  to  them  all,  in  order  that  they  may 
act  together  for  the  one  purpose.  This  is  called  the  respiratory 
center;  it  is  situated  in  the  brain  (in  the  oblongata). 


240  ANATOMY   AND   PHYSIOLOGY 

Normal  respiration  is,  as  we  have  seen,  a  rhythmic  process; 
that  is,  the  demand  for  oxygen  is  met  by  the  act  of  inspiration; 
this  demand  satisfied,  the  passive  chest  walls  sink  back  into  posi- 
tion and  the  lungs  retract,  but  only  for  an  instant;  another 
demand  is  followed  by  another  inspiration  and  the  passive 
expiration,  regularly  repeated  ad  infinitum. 

What  causes  the  respiratory  center  to  make  this  demand?  It 
is  believed  that  the  CO%  in  the  blood,  which  is  flowing  to  the  lungs 
from  the  heart,  is  the  normal  direct  excitant  of  the  center.  Many 
facts  in  our  experience  are  explained  by  this  theory;  e.g.,  after 
several  deep  breaths  the  blood  is  rich  in  oxygen  and  one  is  content 
to  suspend  respiration,  but  after  a  few  seconds  the  oxygen  is  con- 
sumed, the  blood  is  charged  with  GO2  and  the  act  of  inspiration  is 
at  once  stimulated. 

The  same  theory  is  advanced  to  explain  the  cause  of  the  new- 
born infant's  first  inspiration.  With  the  cessation  of  the  blood 
stream  from  the  mother,  oxygen  is  lost,  C02  accumulates  and 
inspiration  follows. 

In  infancy  and  youth  the  rapid  tissue  changes  of  the  growing 
body  cause,  in  the  same  manner,  a  higher  rate  of  respiration  than 
in  adult  life.  So  with  muscle  exercise,  which  sends  the  blood 
coursing  through  the  body  to  gather  its  load  of  C02. 

Whatever  causes  rapid  circulation  causes  rapid  breathing.  This 
is  the  explanation  of  the  increased  respirations  of  fever. 

Reflex  stimuli  of  the  respiratory  center  are  without  number; 
the  whole  sensory  apparatus  affects  it.  Exposure  to  cold  (low 
temperature  of  the  air)  or  sudden  contact  with  a  cold  body,  for 
example  the  chill  of  cold  water,  causes  a  gasp  or  forced  inspiration, 
which  is  soon  followed  by  rapid  breathing.  (The  sudden  contact 
of  the  baby's  body  with  the  surrounding  air  is  probably  a  power- 
ful excitant  to  the  first  respiration,  perhaps  the  principal  one,  and 
often  has  to  be  aided  by  cold  sprinkling.)  Sharp  recurring  pain, 
emotions  of  pleasure,  anger,  surprise,  etc.,  all  have  a  similar  effect. 

Slowing  of  respiration  follows  an  accumulation  of  O;  after  a 
few  deep  breaths  one  may  refrain  from  inspiration  for  a  time 
(for  -from  40  seconds  upward)  according  to  training,  the  blood 
using  the  residual  air  after  the  O  of  the  tidal  and  complemental 
supply  is  exhausted. 

Warmth  disposes  to  moderate  breathing;  a  sense  of  physical 


RESPIRATION  AND  BODY  HEAT  241 

comfort  does  the  same;  reflex  stimuli  are  absent,  the  system  is 
relaxed  and  all  processes  slow  down. 

The  breathing  of  normal  sleep  is  slow  and  regular.  Depressing 
emotions  tend  to  diminish  the  frequency  and  disturb  the  rhythm  of 
respiration.  (Witness  the  "long  breath"  and  frequent  sighing  of 
the  morbidly  depressed  person.) 

In  certain  cerebral  and  other  conditions,  the  respiratory 
center  seems  to  be  dulled,  so  that  it  responds  sluggishly  or  irregu- 
larly, as  in  meningitis  and  apoplexy;  also  in  disease  of  the 
myocardium. 

Action  of  Drugs. — Certain  drugs  are  called  respiratory  stimu- 
lants. Among  the  best  known  are  strychnine  and  atropine. 
Others  are  respiratory  depressants:  as  opium  (in  sufficient  dose), 
ether,  chloroform,  and  many  others. 

Respiration  is  one  of  those  involuntary  processes  in  the  body 
which  we  may  voluntarily  regulate.  We  may,  whenever  we  choose, 
modify  the  rate  and  depth  of  respirations,  breathing  slowly  or 
rapidly,  deeply  or  superficially  at  will.  We  may  even  cease  to 
breathe  for  a  time,  because  the  residual  air  always  present  will  sus- 
tain the  demand  for  oxygen  temporarily,  although  soon  we  lose  con- 
trol and  respiration  will  proceed  with  or  without  any  effort  of  ours. 

Respiration  contributory  to  body  heat  by  providing  oxygen 
for  tissue  change  in  all  parts  of  the  body. 

Muscle  tissue  is  constantly  at  work;  by  rapid  oxidation  the 
muscles  generate  much  heat,  but  only  so  long  as  the  respiratory 
organs  keep  pace  with  the  demand  for  rapid  breathing. 

It  is  natural  to  breathe  more  rapidly  as  well  as  more  deeply  on 
a  cold  day,  because  a  low  temperature  of  the  surrounding  air 
stimulates  (reflexly)  the  various  activities  of  the  body  to  meet  the 
call  for  warmth,  and  the  respiratory  process  must  be  among  the 
first  to  respond.  (The  subject  of  body  heat  is  considered  in 
Chapter  XVIII.) 

The  tissues  which  are  most  active  require  most  oxygen.  Con- 
sequently we  can  create  a  demand  and  obtain  a  supply  by  volun- 
tary muscle  exercise  in  good  air,  thus  feeding  the  blood  and  through 
it  the  viscera  where  also  much  heat  is  generated,  and  the  entire 
body,  with  this  most  important  element  for  tissue  change. 

Summary. — Respiration  is  a  nutritive  process,  an  eliminative 
process  and  a  contributing  source  of  body  heat. 

16 


242  ANATOMY  AND  PHYSIOLOGY 

SPECIAL  MODIFICATIONS  OF  RESPIRATORY  MOVEMENTS 

Rapid  breathing  is  called  hyperpnea. 

Temporary  cessation  of  breathing  is  called  apnea. 

Labored  breathing  is  dyspnea. 

Dyspnea  follows  any  interference  with  the  interchange  of  gases 
in  the  lungs.  It  may  be  caused  by  diminishing  the  entrance  of 
oxygen,  or  by  increasing  the  CO2.  It  is  usually  due  to  imperfect 
circulation  in  the  pulmonary  vessels. 

Asphyxia  is  the  condition  resulting  from  a  complete  cutting 
off  of  oxygen,  or  an  excessive  increase  of  carbon  dioxide.  It  may 
be  sudden  or  gradual,  but  if  unrelieved,  ends  only  in  death. 

The  change  of  color  noted  in  the  face  of  one  suffering  from 
dyspnea,  and  still  more  from  asphyxia,  is  due  to  the  accumulation 
of  carbon  dioxide  in  the  blood. 

In  Cheyne-Stokes  breathing,  a  period  of  apnea  is  followed  by 
respirations  which  are  at  first  faint  and  shallow,  then  gradually 
increase  in  depth  and  rate  until  they  become  either  normal  or 
exaggerated,  when  they  either  cease  abruptly  or  decline  to  another 
period  of  apnea.  This  may  occur  many  times  in  succession,  but 
is  seldom  constant.  It  is  seen  in  the  sleep  of  a  patient  with  fatty 
heart,  sometimes  in  the  sleep  of  children  apparently  well;  often 
in  apoplexy. 

Stertorous  breathing  is  characterized  by  a  loud  snoring  sound; 
it  is  unconscious  and  sometimes  labored. 

The  production  of  artificial  respiration  is  attempted  by  imitat- 
ing Nature's  method.  (See  p.  238.)  By  elevating  the  arms  the 
thoracic  walls  are  spread,  the  lungs  follow,  air  is  drawn  in.  De- 
pressing the  arms  against  the  thorax  presses  the  walls  down,  the 
lungs  are  compressed,  air  is  expelled.  In  this  manner  not  only  is 
the  air  current  set  in  motion  in  the  lungs,  but  an  additional  stimu- 
lus is  created  by  the  expanding  and  subsiding  of  the  lung  cells. 
When  expanded  they  call  for  expiration  to  relieve  them,  and  when 
collapsed  they  demand  inspiration  to  fill  them.  This  is  a  physio- 
logic stimulus  which  is  believed  to  be  constantly  felt  by  the  lung 
tissue  in  health. 

Internal  respiration  will  be  studied  under  Metabolism.  Chapter 
XVIII. 


VENTILATION 


243 


Ventilation. — The  subject  of  ventilation  is  a  broad  one,  since 
so  many  factors  enter  into  the  problem  of  securing  it.  The  rate 
at  which  air  should  be  renewed  is  influenced  by  the  number  of 
people  in  a  room,  also  by  the  occupations  carried  on  therein,  as 
can  be  easily  understood.  Even  in  small  rooms  the  quantity  of 
air  may  be  sufficient,  if  a  constant  current  of  renewal  be  secured. 
The  well-known  morning  " closeness"  of  the  air  of  a  sleeping  room 
is  due  to  the  fact  that  in  the  quiet  of  the  night  the  ordinary  air- 
currents  are  not  present.  It  is  the  lack  of  oxygen  rather  than 
the  excess  of  carbon  dioxide  which  is  felt  and  which  is  in  reality 
the  more  serious. 

Important  Note. — The  importance  of  fresh  air  in  sufficient  quantity  cannot 
be  over-estimated.  One  thousand  cubic  feet  of  space  for  each  adult  (equal 
to  a  room  10  feet  in  height,  length  and  breadth),  renewed  about  three  times 
hourly,  is  not  too  much. 


CHAPTER  XV 
ELIMINATION.     ORGANS  OF  ELIMINATION. 

THE  KIDNEYS 

Having  studied  the  Digestive,  Circulatory  and  Respiratory 
Organs,  or  organs  of  nutrition,  we  will  next  consider  those  which  are 
active  in  the  removal  of  waste  from  the  system  or  the  Organs  of 
Elimination.  They  are  the  kidneys,  skin,  liver  and  lungs,  and  to  a 
lesser  extent,  the  intestinal  canal. 

Of  these,  the  kidneys  alone  are  specially  constructed  for  the 
function  of  elimination  only.  The  skin,  although  mainly  an  organ 
of  excretion  (or  elimination),  has  other  uses  beside  (as  will  be  seen 
in  succeeding  pages). 

The  liver  and  the  lungs  are  included  under  this  heading — the 
liver,  because  certain  waste  products  are  contained  in  the  bile; 
the  lungs,  because  they  are  agents  for  the  removal  of  carbon  dioxide. 
The  intestinal  tract  is  the  avenue  by  which  the  gross  waste  material 
of  the  food  is  expelled,  and  at  the  same  time  it  is  the  main  avenue  of 
entrance  into  the  system  of  nutritive  material.  Therefore  the 
lungs,  liver,  and  intestine  are  found  in  both  lists  of  organs,  nutritive 
and  eliminative. 

THE  KIDNEYS 

The  kidneys  (renes)  are  the  most  important  organs  of  excretion. 
They  separate  certain  waste  matters  from  the  blood,  in  a  definite 
form  for  removal  from  the  body;  this  is  their  special  function. 

They  are  situated  for  the  most  part  in  the  posterior  lumbar 
region,  just  in  front  of  the  quadratus  lumborum  muscles,  extending 
from  about  the  tenth  rib  to  within  two  or  three  inches  from  the 
crest  of  the  ilium.  They  are  shaped  like  a  bean,  about  four  or 
five  inches  long  and  one  and  one-half  inches  wide,  with  the  concave 
border,  or  hilus,  turned  toward  the  spinal  column;  and  they  are 
imbedded  in  fat  behind  the  peritoneum.  This  is  the  fatty  capsule; 
outside  of  it  a  thin  layer  of  fascia  extends  across  both  kidneys, 
being  attached  to  the  fascia  in  front  of  the  lumbar  muscles  and 
lumbar  spine.  It  is  called  the  renal  fascia. 

244 


STRUCTURE    OF   KIDNEY 


245 


The  other  abdominal  organs  are  in  front  of  or  above  and 
below  the  kidneys,  so  the  natural  result  of  this  arrangement  is 
that  they  are  stationary,  the  only  stationary  organs  in  the  abdomen, 
the  others  all  move  in  respiration,  digestion,  defecation,  micturi- 
tion, parturition. 

The  kidney  is  hollow,  the  cavity  within  being  called  the  sinus. 
It  is  covered  by  &  fibrous  capsule  which  also  lines  the  sinus. 


Left  kidney 


Left  ureter 


Right  ureter 


FIG.  162. — THE  KIDNEYS.     (Morris.} 

Structure. — A  kidney  is  a  mass  of  minute  tubes,  the  uriniferous 
tubules  lined  with  epithelial  cells,  which  perform  the  real  work  of 
the  organ.  At  the  beginning  of  each  is  a  bulb-like  enlargement, 
indented  to  form  a  deep  hollow  (Bowman's  capsule,  Fig.  163) 
which  encloses  a  tuft  of  renal  capillaries.  The  capsule  and  vessels 
together  constitute  a  Malpighian  or  renal  corpuscle.  As  the 
tubule  leaves  the  bulb  it  twists  and  turns  many  times  and  is  called 
the  convoluted  tubule.  It  has  a  network  of  blood-vessels  around  it. 
The  convoluted  tube  finally  becomes  straight,  and  at  last  several 
straight  ones  unite  to  form  a  collecting  tube  which  opens  into  the  sinus. 

Malpighian  corpuscles  and  convoluted  tubes  occupy  most  of 
the  portion  of  the  kidney  near  the  surface,  forming  the  cortex 


246 


ANATOMY   AND   PHYSIOLOGY 


(or  cortical  portion).     The  straight  or  collecting  tubes  are  grouped 
together  into  pyramids,  pointing  toward  the  interior  and  forming 

the  medullary  portion.  The 
apex  of  each  pyramid  pro- 
jects into  the  sinus,  pre- 
senting the  openings  of  sev- 
eral collecting  tubes -(Fig. 
164). 

The  cells  which  line 
this  system  of  tubes  do  the 
work  of  excreting  the  urine 
from  substances  in  the 
blood,  thus  relieving  it  of 
poisonous  elements  which 
would  surely  cause  death 
if  allowed  to  remain. 

The  urine  is  conducted 
from  the  kidney  to  the  blad- 
der through  the  ureter,  a 
slender  musculo-fibrous 
duct  about  twelve  inches 

long,  the  upper  end  of  which  is  enlarged  and  called  the  pelvis  of 
the  kidney.  (It  occupies  the  sinus.)  It  has  a  thin  layer  of  muscle 
fibers  and  is  lined  with  mucous  membrane. 
The  two  ureters  extend  into  the  true  pelvis 
to  the  base  of  the  bladder,  where  they 
terminate  about  one  inch  apart. 

The  Urinary  Bladder  is  the  receptacle 
and  reservoir  for  the  urine  and  is  situ- 
ated in  the  pelvis  just  behind  the  pubic 
bones;  between  them  and  the  rectum  in 
the  male  pelvis,  between  them  and  the 
vagina  and  uterus  in  the  female  pelvis. 
It  is  a  non-striated  muscular  sac,  lined 
with  mucous  membrane  which  lies  in  ir- 
regular folds  when  the  sac  is  empty,  but 
becomes  smooth  when  it  is  filled.  It  has 
a  covering  of  peritoneum  above  and  posteriorly  but  not  in  front. 
The  upper  portion  of  the  bladder  is  the  summit  or  vertex;  the 


FIG.  163. — SCHEME  OF  THE  RENAL  OR 
MALPIGHIAN  CORPUSCLE. 

i.  Interlobular  artery.  2.  Afferent  vessel. 
3.  Efferent  vessel.  4.  Outer  wall.  5.  Inner  wall. 
6.  Glomerulus.  7.  Neck  of  tubule.— (Stohr.} 


FIG.  164. — SECTION  OF 
KIDNEY.— (Potter.} 


THE    URETHRA 


247 


lower  part  is  the  base  or  fundus.  There  are  three  openings  in  the 
bladder  wall,  two  for  the  entrance  of  urine  and  one  for  expelling  it. 

The  urine  enters  through  the  two  ureters  (Fig.  162)  or  ducts 
of  the  kidney,  which,  having  reached  the  pelvis,  proceed  below 
the  broad  ligaments  (Fig.  138))  to  run  forward  and  enter  the  base 
of  the  bladder,  there  discharging  the  urine. 

The  opening  for  the  escape  of  the  urine  is  called  the  internal 

Bladder        Uterus 


Urethra 


Vaginal 
orifice 


Anus  (rectum  distended) 


FIG.  165. — PELVIC  ORGANS,  FEMALE  PELVIS. — (Holden.) 
Dotted  lines  indicate  peritoneum. 

orifice.  It  leads  into  a  canal  called  the  urethra  which  ends  at  the 
external  orifice  (or  meatus),  and  through  it  the  urine  is  expelled 
from  the  body.  The  internal  orifice  is  guarded  by  circular  muscle 
fibers  forming  a  sphincter — the  sphincter  vesica  (sphincter  of  the 
bladder).  The  part  where  the  internal  orifice  is  located  is  often 
called  the  neck  of  the  bladder. 

The  openings  of  the  ureters  are  about  one  inch  from  the  internal 
orifice,  and  the  same  distance  apart,  thus  these  three  openings 
mark  the  corners  of  a  triangle  at  the  base  of  the  bladder,  called 
the  trigone. 

The  urethra  is  a  fibro-muscular  canal  lined  with  mucous  mem- 
brane. It  begins  at  the  internal  orifice  of  the  bladder,  ends  at  the 
external  orifice  or  meatus  urinarius,  and  conducts  the  urine  from 
the  body. 


248  ANATOMY   AND   PHYSIOLOGY 

The  length  of  the  male  urethra  is  from  seven  to  eight  inches. 

The  female  urethra  is  about  one  and  one-half  inches  long  and 
1/4  in  wide,  but  is  very  distensible.  It  curves  slightly  downward 
toward  the  external  meatus. 

Clinical  note. — The  catheter  should  pass  a  little  upward  after  entering  the 
urethra  (Fig.  165). 

A  urethral  caruncle  is  an  exceedingly  painful  little  tumor 
projecting  from  the  urethral  mucous  membrane.  It  is  a  collection 
of  sensitive  blood-vessels  and  nerves. 

When  empty  the  bladder  lies  entirely  in  the  pelvis,  but  if  it 
contains  more  than  eight  ounces  it  begins  to  rise  into  the  abdo- 
men. It  has  been  known  to  extend  as  high  as  the  umbilicus. 

Surgical  notes. — Since  the  peritoneum  covers  the  vertex  and  a  portion  of 
the  posterior  surface  only,  the  bladder  may  be  entered  in  front  through  an 
incision  just  above  the  symphysis  pubis  without  wounding  the  peritoneum. 

Cystitis  is  inflammation  of  the  bladder. 

PHYSIOLOGY    OF    THE    KIDNEYS    AND    ACCESSORY 

ORGANS 

This  consists  in  the  removal  of  waste  substances  from  the  blood  in  the 
form  of  urine  and  expelling  it  from  the  body. 

The  process  of  excretion  in  the  kidney  is  one  of  filtration  and  secretion. 
The  kidney  has  a  large  blood  supply  through  the  renal  artery,  which  enters 
at  the  hilum  and  divides  at  once  into  several  branches.  The  capillaries  from 
these  arteries  are  very  numerous.  They  enter  first  the  capsule  of  the  Mal- 
pighian  body  as  afferent  vessels  and  form  a  cluster  or  tuft  there  (the  glomerulus) 
from  which  the  water  and  salts  are  filtered  out  and  pass  into  the  tubule. 
They  then  leave  the  capsule  as  efferent  vessels  and  twist  themselves  about  the 
convoluted  tubules,  whose  epithelial  cells  select  (secrete}  the  organic  substances 
— urea,  uric  acid  and  others.  These  are  washed  down,  by  the  watery  solution 
coming  from  the  capsule,  to  the  collecting  tubes  of  the  pyramids  and  there 
discharged  into  the  pelvis  of  the  kidney,  as  urine;  the  amount  of  urine  excreted 
varies  greatly,  but  in  the  adult,  in  health,  averages  48  ounces  or  3  pints  daily; 
it  is  directly  affected  by  the  quantity  of  fluid  which  the  person  drinks,  the 
amount  of  perspiration  formed  and  in  other  ways. 

Children  excrete  more  than  adults  in  proportion  to  the  body 
size,  averaging  nearly  one-half  of  the  adult  quantity  at  the  age  of 
five  years.  This  is  probably  due  to  the  fact  that  their  dietary 
contains  more  fluid,  also  their  metabolism  or  tissue  change  is 
more  rapidly  carried  on,  creating  more  waste  material  proportion- 
ately, to  be  eliminated. 


URINE  249 

Clinical  note. — Renal  colic  is  caused  by  the  attempt  to  pass  a  stone  or 
calculus  through  the  ureter. 

Urine  is  excreted  more  rapidly  in  the  middle  of  the  day,  from  one 
to  two  o'clock,  and  after  waking  from  sleep;  less  rapidly  between 
two  and  four  in  the  afternoon. 

Micturition  is  the  act  of  expelling  the  urine  from  the  bladder 
(clinically,  it  is  often  called  urination).  The  contraction  of 
certain  muscles  of  the  bladder  wall  opens  the  sphincter  vesicce  and 
the  urine  escapes  through  the  urethra.1 

Although  under  the  control  of  the  will  after  a  preliminary 
period  of  education,  micturition  is  sometimes  involuntary,  con- 
stituting enuresis  or  urinary  incontinence.  This  may  be  due  to  the 
presence  of  irritating  substances  in  the  urine  which  affect  the  mus- 
cles of  the  bladder,  or  to  too  great  concentration,  or  simply  to  an 
excessive  quantity  of  fluid,  or  to  lack  of  control  by  the  nervous 
system — or  various  causes  of  a  reflex  character. 

Retention  of  urine  means  accumulation  in  the  bladder  owing 
to  inability  to  expel  it.  This  may  be  due  to  one  or  more  of  several 
causes:  lack  of  muscle  tone  and  feeble  contracting  power;  nervous 
contraction  (closure)  of  the  sphincter;  impaired  sensibility  of 
vesical  nerves;  loss  of  spinal  nerve  control;  obstruction  at  the  neck 
of  the  bladder,  etc.  This  inability  may  be  so  complete  that  the 
bladder  becomes  entirely  filled  and  the  sphincter  can  no  longer  act; 
the  urine  dribbles  away  and  the  condition  is  one  of  ll  retention  with 
overflow"  from  inability  of  the  bladder  to  contract. 

Suppression  of  urine  means  inability  of  the  kidney  to  act;  no 
urine  is  excreted. 

Urine  is  a  watery  fluid  of  amber  color,  somewhat  heavier  than 
water  (the  normal  specific  gravity  is  1010-1020),  with  a  charac- 
teristic odor,  and  having  the  temperature  of  the  body  at  the  time 
of  voiding.  Its  reaction  is  normally  acid.  This  is  due  to  the 
character  of  the  diet  of  man,  which  in  most  cases  contains  more 
or  less  of  animal  food.  Certain  salts  (acid  phosphates)  derived 
from  this  mixed  diet  cause  the  acidity  of  the  urine.  It  is  more 
marked  in  the  morning  before  food  is  taken.  With  a  diet  of 
vegetables  and  cereals  the  reaction  is  neutral  or,  perhaps,  alkaline. 

The  coloring  matter  is  derived  from  bile  pigments;  it  is  deep  or 

1  All  sphincters  are  opened  in  this  manner — by  action  of  the  walls  of  the  cavity 
which  they  guard. 


250  ANATOMY   AND   PHYSIOLOGY 

pale,  as  the  urine  contains  less  or  more  water.  The  weight  is  due 
to  the  salts  contained,  both  organic  and  inorganic  (or  mineral)  and 
this  also  is  modified  by  the  amount  of  water.  Both  water  and  salts 
vary  markedly  with  the  dietary  of  the  individual. 

Clinical  notes. — The  color  and  odor  may  both  be  modified  by  drugs  or  by 
articles  of  food.  (For  example,  turpentine  causes  the  odor  of  violets,  while 
that  imparted  by  asparagus  is  well  known.)  Urine  containing  blood  cells  is 
smoky  in  appearance;  and  every  nurse  knows  what  methylene  blue  will  do. 

The  most  important  substance  to  be  excreted  in  the  urine  is 
urea.  This  represents  the  absolutely  useless  material  remaining 
from  protein  foods.  It  is  prepared  for  excretion  in  the  liver.  It 
is  a  substance  which  if  allowed  to  accumulate  in  the  system 
becomes  a  deadly  poison,  causing  death  by  uremia. 

Uric  acid  is  protein  waste  in  another  form  and  smaller  quantity. 
Phosphates  of  sodium,  potassium  and  calcium  are  present  normally, 
also  other  mineral  salts,  sodium  chloride  (common  salt)  being  the 
most  abundant. 

Water  is  necessary  for  the  solution  of  all  these  solids.  This 
varies  in  quantity  in  many  systemic  conditions.  Increased 
activity  of  the  lungs  and  skin,  for  example,  removes  water  from 
the  blood  and  thus  makes  the  urine  scanty  but  more  dense  and 
very  acid. 

Two  sets  of  causes  affect  the  quantity  of  urine:  i.  those  which  increase 
or  diminish  blood  pressure  in  the  kidney;  2.  those  which  influence  the  secretory 
activity  of  the  cells  which  line  the  tubules.  Increased  blood  pressure  increases 
the  flow  of  water  and  salts  (in  the  glomeruli) ;  toxic  substances  (organic  waste) 
stimulate  the  excretory  function  of  the  cells  in  the  tubules. 

The  importance  of  the  kidneys  is  shown  by  the  fact  that  the 
daily  quantity  of  urine  normally  produced,  equals  the  excretion 
of  the  lungs,  skin  and  intestinal  tract  together. 

The  average  amount  of  solids  in  the  body  (to  be  excreted) 
does  not  vary  greatly,  but  the  quantity  of  water  ingested  varies 
constantly  and  the  specific  gravity  changes  with  the  water  supply. 

The  quantity  and  the  specific  gravity  bear  a  pretty  constant  ratio  to 
each  other.  As  a  rule,  the  abundant  urine  is  light  in  weight  (low  specific 
gravity}.  Conversely,  the  scanty  urine  is  dense  and  heavy  (high  specific 
gravity}.  A  notable  exception  is  the  urine  of  diabetes  mellitus,  which  is  very 
abundant  and  at  the  same  time  has  high  specific  gravity,  owing  it  to  the 
sugar  content. 


NEPHRITIS,    RENAL    CASTS  251 

Whatever  increases  blood  pressure  increases  the  amount  of 
urine;  many  diuretic  medicines  act  in  this  manner.  Muscle 
exercise  not  only  increases  blood  pressure,  but  stimulates  the 
secreting  cells  by  the  toxic  substances  which  arise  normally  from 
rapid  metabolism  and  are  carried  to  the  kidney  by  the  quickened 
circulation. 

Nervous  excitement  and  hysteria  cause  an  abundant  pale  urine. 
Cold  weather  and  moist  air  both  discourage  the  activity  of  the  skin 
—therefore,  they  increase  the  action  of  the  kidneys. 

On  the  other  hand,  if  the  system  rids  itself  of  water  in  other 
ways,  as  by  excessive  perspiration,  diaphoretic  medicines,  hot  packs, 
etc.,  the  urine  will  be  diminished,  but  it  will  have  a  high  specific 
gravity. 

Clinical  notes. — i.  The  toxic  substances  which  are  present  in  the  blood  in 
fevers  are  abnormal  to  the  kidney  and  modify  its  action  so  that  the  urine  is 
scanty  and  dense. 

2.  Nephritis  is  inflammation  of  the  kidney.  In  one  form  (acute 
Bright' s  disease)  it  causes  a  scanty  and  dense  urine;  in  another  and 
chronic  form  an  abundant  dilute  urine.  (When  waste  ceases  to 
appear  we  know  that  the  cells  are  not  secreting.) 

3.  Certain  poisons  which  are  swallowed  (bichloride  of  mercury  for 
example)  cause  such  intense  irritation  of  the  cells  in  the  tubules  that 
they  are  seriously  injured  and  may  be  destroyed. 

4.  Renal  casts.     (Tube  Casts.} — Irritation  of  the  kidney  struc- 
ture so  changes  its  tissue  that  plastic  material  from  the  blood 
exudes  into  the  tubules  and  is  there  moulded  into  their  shape, 
forming  casts.     Hyaline  casts  are  transparent  (being  the  simplest 
form).     Granular  casts  show  a  more  advanced  stage  of  trouble. 
Epithelial  casts  have  epithelial  cells  added;  urate  casts  are  common 
in  rheumatism  and  tonsillitis,  etc.,  etc. 

5.  Casts  signify  renal  congestion,  always;  if  persistent  they 
indicate  inflammation. 

6.  Albuminuria,  or  the  presence  of  albumin  in  the  urine,  is  also 
an  evidence  of  congestion  or  of  disease.     It  is  often  temporary, 
disappearing  with  the  disappearance  of  the  cause,  which  may  be 
fever,  the  inhalation  of  ether,  the  use  of  alcohol,  etc. 

7.  Albumin  is  often  due  to  conditions  outside  of  the  kidney 


252  ANATOMY   AND   PHYSIOLOGY 

tissue.  It  is  seen  in  anemia  (chronic) ;  with  the  presence  of  pus, 
or  accompanying  the  admixture  of  vaginal  discharge. 

Important  notes. — Specimens  for  complete  urine  analysis  should 
represent  the  activity  of  the  kidneys  during  twenty-four  hours,  as 
the  composition  of  the  urine  varies  during  exercise  and  rest,  in 
fasting  or  when  food  is  taken,  and  so  forth. 

It  will  often  be  the  duty  of  the  nurse  to  test  the  chemical  re- 
action by  the  use  of  litmus  paper.  Acidity  is  due  to  kidney  con- 
ditions; alkalinity  to  bladder  conditions  (usually).  (The reaction 
is  influenced  by  drugs.) 

Polyuria  is  excessive  secretion  of  urine. 

Oliguria  is  diminished  secretion — scanty  urine. 

Hematuria  is  the  secretion  of  bloody  urine. 

Hemoglobinuria  is  the  secretion  of  urine  which  contains  the 
colored  portion  (hemoglobin)  of  disintegrated  red  blood  cells. 

Glycosuria  is  the  secretion  of  urine  containing  grape  sugar  or 
glucose. 

ABNORMAL  POSITIONS  OF  THE  KIDNEY 

A  kidney  may  develop  in  some  unusual  location ;  if  it  is  fixed  in 
that  position  it  is  called  a  misplaced  kidney. 

A  floating  kidney  is  one  which  develops  in  an  unusual  location 
but  is  not  fixed  in  that  position.  It  then  has  a  covering  of  peri- 
toneum (meso-nephron)  like  that  of  other  abdominal  organs  and 
moves  freely. 

A  movable  kidney  is  one  developed  in  the  proper  place,  but  either 
through  loss  of  the  fatty  capsule,  or  relaxation  of  tissues  generally, 
it  moves  in  its  capsule  of  fascia.  It  makes  excursions  upward  and 
downward  following  the  movements  of  the  diaphragm  and  may 
be  palpated.  It  may  become  quite  displaced  and  even  fixed  in  the 
abnormal  position  constituting  a  dislocated  kidney. 

During  development  the  kidney  consists  of  lobules  which  later 
become  fused  into  a  uniform  structure;  persistence  of  this  lobu- 
lated  arrangement  (infantile  kidney)  may  be  observed  at  autopsy. 
This  is  not  important. 

Occasionally  one  kidney  may  be  absent.  Sometimes  two  kid- 
neys are  fused  into  one,  making  an  arched  or  horse-shoe  kidney. 


CHAPTER  XVI 
ELIMINATION 

THE  SKIN 

The  skin,  or  integument,  is  the  elastic  and  protective  covering 
of  the  body.  It  covers  the  entire  exterior  surface  and  is  continuous 
at  the  orifices  of  the  body  with  the  mucous  membranes  of  the 
interior  surfaces.  It  consists  of  two  layers,  a  deep  one  called  the 


FIG.  166. 

Showing  the  layers  of  the  skin  (greatly  magnified),  with  the  sweat  glands  and  oil 
glands,  and  a  hair  in  its  follicle.     (Brubaker.) 

corium,  also  the  cutis  vera  or  true  skin,  or  derma,  and  a  superficial 
one  called  the  epidermis  or  cuticle. 

The  corium  or  "true  skin"  (cutis  vera)  is  a  vascular,  elastic  and 
sensitive  layer,  red  and  soft;  resting  upon  a  loose  subcutaneous 
tissue.  Its  deep^portion  is  well  supplied  with  vessels  and  nerves 

253 


254 


ANATOMY   AND   PHYSIOLOGY 


(tactile  cells)  supported  by  a  fibrous  and  elastic  network  (reticular 
layer)  which  contains  non-striated  muscle  fibers  and  fat.  In  this 
layer  are  the  blood-vessels,  nerves  and  lymphatics  which  are 
exceedingly  numerous. 

Tiny  projections  called  papilla  rise  from  this  network  portion, 
many  papilla  containing  special  nerve-endings  called  touch  cor- 
puscles. They  all  contain  at  least  a  single  loop  of  blood-vessels. 
Some  contain  several  loops — these  are  vascular  papilla.  They 

are  arranged  in  rows  form- 
ing ridges  which  are  circular 
on  the  front  of  the  finger 
tips.  It  is  a  remarkable  fact 
that  no  two  fingers  or  toes 
are  alike  in  this  respect,  hence 
the  thumb-  or  finger-mark  is  a 
means  of  identification.  Its 
value  is  never  lost,  even  in 
old  age,  as  these  ridges  are 
permanent. 

The  papillae  constitute  a  "papil- 
lary layer."  There  are  still  other 
nerve  endings  in  the  corium  for  different  sensations.  These  are  nerve 
papillae. 

The  epidermis  (or  cuticle)  completely  covers  the  corium.  It 
consists  of  layers  of  cells  of  varying  character  and  thickness.  The 
deeper  cells  are  soft  and  nucleated,  but  near  the  surface  they 
become  flat  and  dry,  until  finally  they  are  mere  tiny  scales.  It  has 
no  vessels  and  scarcely  any  nerves,  consequently  it  is  not  sensitive 
and  does  not  bleed.  It  is  this  which  comes  away  after  the  action 
of  a  blister. 

The  color  of  the  skin  depends  partly  upon  the  blood  supply 
and  more  upon  pigment  or  coloring  matter,  which  is  deposited  in 
the  deep  layers  of  the  epidermis  (and  the  superficial  layers  of  the 
derma).  The  pigment  varies  in  different  people  and  races. 

In  all  races,  the  color  is  deeper  in  exposed  portions  of  the  skin 
(face  and  hands),  about  the  arms,  axillae,  and  the  areolae  of  the 
mammary  glands.  It  is  lighter  than  elsewhere  on  the  palms 
and  soles  of  the  colored  races.  Exposure  to  heat  as  well  as  light 
deepens  it. 


FIG.  167. — TACTILE  CELLS  FROM  SNOUT 
OF  PIG.  a.  Tactile  cell.  m.  Tactile  disc. 
n.  Nerve-fiber. — (Stirling.') 


CHARACTERISTICS    OF    SKIN  255 

Clinical  notes. — The  insensitive  and  bloodless  character  of  the  epidermis 
or  cuticle  is  plainly  demonstrated  in  the  dressing  of  a  blister,  when  it  is 
incised  to  allow  the  escape  of  serum  which  has  accumulated  between  it  and 
the  corium  or  true  skin.  Again,  the  fact  of  the  pigment  deposit  in  the  deep 
layers  of  the  epidermis  is  shown  when  the  blister  is  on  the  skin  of  a  colored 
person;  the  pigment  comes  away  with  the  elevated  epidermis. 

The  surface  of  the  epidermis  is  continually  wearing  away  and  new  layers 
of  epithelial  cells  are  exposed,  to  become  dry  and  scaly,  and  to  be  shed  in 
their  turn.  It  varies  in  thickness  according  to  the  degree  of  friction,  or  pres- 
sure, or  exposure  which  it  encounters.  Witness  the  palms  of  the  hands  and 
the  soles  of  the  feet,  the  back  of  the  neck  and  shoulders,  the  scalp,  and — in 
contrast — the  thin  skin  of  the  flexor  surfaces  of  joints,  the  groins,  medial 
surfaces  of  limbs,  etc.  (It  is  in  these  latter  locations  that  inunctions  are 
given.) 

The  vascularity  of  the  skin  is  evident  from  the  free  flow  of 
blood  after  the  slightest  cut.  There  are  two  special  networks 
(rete)  of  capillaries,  one  just  beneath  the  true  skin,  and  one  at 
the  bases  of  the  papillae. 

The  elasticity  of  the  skin  is  demonstrated  when  a  cut  is  made 
through  the  corium.  The  edges  retract  and  some  effort  is  required 
to  bring  them  together  again.  The  elasticity  is  due  not  only  to  the 
elastic  fibers  in  the  deep  layer  of  the  corium,  but  to  muscle  fibers, 
small  though  they  be. 

The  sensibility  of  the  skin  is  very  marked.  Nerve-ends  exist 
in  the  corium  for  various  sensations,  a  few  fibrils  being  connected 
with  the  deep  layer  of  the  epidermis.  (See  The  Skin  as  the  Organ 
of  Touch,  p.  327.) 

The  greater  portion  of  the  skin  is  loosely  connected  to  the  parts 
beneath  it  by  subcutaneous  areolar  tissue  (see  p.  5),  so  that  it  is 
movable.  When  this  contains  fat  it  is  called  the  panniculus 
adiposus.  There  is  no  fat  under  the  skin  of  the  scrotum,  eyelids 
or  posterior  surface  of  the  external  ear. 

(The  skin  of  the  scalp  is  not  very  movable,  except  as  the  entire 
structure  is  moved  by  the  epicranial  muscle.) 

The  glands  of  the  skin  are  in  the  corium;  their  ducts  pass 
through  the  epidermis  to  open  upon  the  surface.  They  are  of 
two  kinds — the  sebaceous  glands  and  the  sweat  glands  (sudoriferous 
glands) . 

The  sebaceous  glands  are  found  in  the  skin  of  all  parts  of  the 
body  except  the  palms  and  soles.  They  are  most  numerous  upon 
the  face.  They  produce  an  oily  substance  called  sebum  which 


256  ANATOMY  AND   PHYSIOLOGY 

renders  the  skin  soft  and  pliable.  Their  ducts  open  into  the  de- 
pressions (follicles)  for  the  roots  of  hairs,  consequently  they  pre- 
serve the  softness  and  glossiness  of  the  hair. 

Ear  wax,  or  cerumen,  is  secreted  by  specialized  glands  in  the 
auditory  canal  (ceruminous  glands) . 

Note. — The  vernix  caseosa  which  is  found  upon  the  skin  of  the  new-born 
child  is  an  accumulation  of  sebaceous  matter  which  has  served  to  protect  the 
skin  from  the  effect  of  long  submersion  in  the  amniotic  fluid.  . 

The  sweat  glands  (sudoriferous  glands)  are  found  in  the  skin  of 
the  entire  body.  Each  gland  consists  of  a  coiled  tube  embedded 
in  the  corium,  with  a  duct  opening  upon  the  surface;  these  ducts 
open  upon  the  ridges  made  by  the  rows  of  papillae.  With  an 
ordinary  magnifying  glass  the  droplets  of  sweat  may  be  seen. 

The  sweat  or  perspiration  is  a  thin  watery  fluid  (highly  acid, 
but  saline  to  the  taste),  containing  a  number  of  substances  in  solu- 
tion, derived  from  the  vessels  in  the  network  of  the  corium.  The 
most  important  are  salt,  phosphates,  urea  and  carbon  dioxide. 

It  is  estimated  that  the  2,000,000  or  more  glands  secrete  nearly 
a  liter  of  perspiration  daily,  in  health.  The  process  goes  on  con- 
tinually; when  the  rate  of  excretion  is  moderate  and  uniform  we 
are  not  aware  of  it,  because  the  moisture  is  removed  in  various 
ways  as  soon  as  formed — this  is  insensible  perspiration.  When 
the  removal  does  not  keep  pace  with  the  production,  the  accumu- 
lation on  the  skin  becomes  sensible  perspiration. 

APPENDAGES  OF  THE  SKIN 

The  appendages  of  the  skin  are  the  glands  already  described, 
the  nails  and  the  hairs. 

The  nails  are  hard  but  elastic  structures  belonging  to  the  cuti- 
cle (being  modifications  of  its  epithelium).  They  give  protection 
to,  and  add  power  and  ease  in  using  the  digits.  The  body  of  the 
nail  lies  upon  a  bed  of  corium  called  the  matrix,  from  which  it 
grows;  if  the  matrix  be  destroyed  the  nail  is  lost  and  no  new  one 
will  grow  in  its  place.  The  root  of  the  nail  is  embedded  in  a  fold  of 
skin;  the  white  semicircle  at  the  root  is  called  the  lunula  (little 
moon). 

Clinical  note. — The  body  of  the  nail  adheres  firmly  to  the  true  skin. 
Much  force  is  required  for  its  removal. 


THE   HAIRS  257 

The  hairs  also  belong  to  the  cuticle.  They  are  distributed 
over  the  greater  part  of  the  surface  of  the  body,  being  conspicuous 
on  the  scalp  by  their  size  and  length. 

A  hair  consists  of  a  root  and  a  shaft.  The  bulb  or  (enlargement 
of  the)  root  rests  upon  a  minute  hair  papilla  in  the  bottom  of  a 
depression  called  a  hair  follicle.1  The  nerves  and  blood-vessels  do 
not  run  beyond  the  papilla. 

The  shaft  extends  outward  from  the  root,  and  contains  the 
pigment  which  decides  the  color  of  the  hair. 

The  main  body  of  the  shaft  consists  of  fibrous  or  cortical  sub- 
stance. In  this  is  the  pigment  of  dark  hairs,  but  only  minute  air 
spaces  in  white  hairs.  In  all  coarse  hairs  except  those  of  the  scalp, 
and  in  the  roots  of  most  hairs,  a  central  pith  or  medulla  exists 
within  the  fibrous  substance.  The  shaft  is  covered  with  a  cuticle 
of  flat  scales  which  overlap  each  other. 

The  hairs  lie  obliquely  on  the  skin  but  may  be  made  to  stand 
erect  by  the  contraction  of  a  tiny  muscle  bundle  placed  at  the  root 
of  each  one.  These  are  the  erectors  of  the  hairs.  It  is  their  action 
which  gives  the  appearance  called  "goose-flesh."  The  softness 
and  the  gloss  of  hair  are  due  to  the  oil  which  is  poured  into  the 
follicles  by  the  oil  glands. 

Note. — The  fine  hair  on  the  skin  of  the  new-born  child  is  called  lanugo. 
It  begins  to  grow  at  about  the  fifth  month  of  intra-uterine  life,  and  wears 
away  soon  after  birth,  although  some  remains  permanently. 

The  hairs  which  border  the  eyelids  are  called  cilia.  The  hairs 
of  the  eyebrows  are  super  cilia.  Those  of  the  nostrils  are  vibrissa; 
of  the  head,  capili;  of  the  beard,  barba. 

PHYSIOLOGY  OF  THE  SKIN 

The  skin  has  a  triple  function.  It  is  the  protective  covering  of 
the  body;  an  organ  of  excretion  and  an  organ  of  the  special  sense 
of  touch.  Also,  it  aids  in  regulating  body  temperature. 

As  a  protective  it  is  mechanical  only;  the  insensitive  layers 
receiving  first  the  impressions  of  external  forces — heat,  cold,  blows, 
etc.,  diminish  their  effects  on  deeper  and  sensitive  ones. 

As  an  organ  of  touch  it  is  referred  to  on  page  327. 

1  In  the  case  of  curly  hair  the  opening  of  the  follicle  leads  inward  in  a  curved  or 
spiral  direction. 

17 


258  ANATOMY   AND   PHYSIOLOGY 

Its  most  important  function  is  to  secrete  perspiration.  Per- 
spiration is  a  clear  watery  fluid  consisting  of  a  solution  of  certain 
waste  products  of  metabolism  (tissue  waste),  in  other  words,  water 
and  solids.  It  is  acid  in  reaction;  saline  to  taste.  The  quantity 
excreted  by  a  healthy  active  person  in  twenty-four  hours  has  been 
estimated  as  one  quart. 

Although  the  amount  of  solids  in  the  perspiration  is  small,  it 
is  enough  to  relieve  the  system  if  the  kidneys  are  disabled,  or  to 
embarrass  it  if  retained.  Urea  is  one  of  the  substances  contained 
in  perspiration,  and  in  diseased  conditions  of  the  kidneys  the  skin 
is  able  to  excrete  an  increased  quantity  of  urea. 

The  removal  of  tissue  waste  is,  however,  not  the  only  important 
use  of  perspiration.  By  bringing  water  to  the  surface  of  the  skin, 
it  is  a  most  efficient  agent  for  regulating  the  temperature  of  the  body. 
Muscle  exercise,  for  example,  which  increases  heat  production,  is 
accompanied  by  increased  activity  of  the  sweat  glands,  and  the 
consequent  evaporation  of  water  carries  off  the  excess  of  heat 
generated  in  the  muscles.  Again,  high  temperature  of  the  sur- 
rounding atmosphere  causes  dilatation  of  the  cutaneous  vessels, 
and  more  perspiration  and  consequent  evaporation.  Conversely, 
a  cold  atmosphere  stimulates  the  cutaneous  vessels  to  contract, 
and  stops  the  production  of  sensible  perspiration.  All  of  this 
activity  is,  of  course,  a  response  to  the  controlling  force  of  nerve 
centers  which  regulate  blood  supply,  and  stimulate  secretory 
action. 

Clinical  note. — From  these  facts  one  may  understand  why  it  is  so  impor- 
tant to  conserve  the  surface  temperature  of  a  patient  with  nephritis,  or  with 
diminution  of  urine  from  any  cause,  by  the  use  of  blankets  and  warm  clothing; 
and  to  increase  it  oftentimes  by  the  use  of  hot  baths,  packs,  etc. 

In  health  the  quantity  of  perspiration  is  modified  by  the  die- 
tary, particularly  by  the  amount  of  liquid  taken,  and  the  kind  of 
liquid;  also  by  the  character  of  clothing,  the  season  of  the  year, 
temperature  of  the  atmosphere,  etc. 

It  may  be  noted  that  the  activities  of  the  skin  and  kidneys 
alternate  with  change  of  season;  in  summer  when  the  skin  is  active 
the  urine  is  scanty.  In  winter,  when  the  skin  is  inactive  the  urine 
is  free. 

Drugs  which  increase  the  production  of  perspiration  are  called 
diaphoretics.  Aconite  and  sweet  spirits  of  nitre  are  familiar  exam- 


ACTIVITIES    OF    THE    SKIN  259 

pies.  Hot  drinks  and  muscular  effort  assist  diaphoresis.  Nervous 
excitement,  as  fear,  pain,  nausea,  produces  the  same  effect.  The 
toxins  of  certain  diseases  also  cause  excessive  perspiration,  as  in 
the  nocturnal  sweating  of  tuberculosis,  the  crisis  of  pneumonia, 
and  other  instances. 

In  fevers,  cutaneous  vessels  are  dilated,  but  the  nerve  stimulus 
to  cell  action  is  dulled  and  the  skin  remains  dry. 

Some  other  diseases  have  a  similar  effect;  loss  of  water  by 
colliquative  diarrhea  (characterized  by  profuse  liquid  stools)  leaves 
the  skin  dry.  In  diabetes  mellitus  a  very  troublesome  symptom 
is  dryness  of  the  skin  with  pruritus  or  itching  (and  a  tendency  of 
the  connective  tissue  to  break  down  in  boils). 

The  effect  of  baths  upon  the  skin  is  to  abstract  heat,  improve 
the  tone  of  cutaneous  structures,  and  favor  the  action  of  the  glands. 

In  renal  diseases,  activity  of  the  skin  is  to  be  promoted;  in  fevers, 
activity  of  the  kidneys,  as  well  as  of  the  skin. 

The  skin  has  a  slight  degree  of  absorbent  action  in  the  areas 
where  it  is  thinnest;  this  power  is  utilized  for  inunctions. 

Clinical  note. — The  skin  should  be  well  rubbed  until  it  is  warm  and  quite 
dry  of  perspiration  or  oil  before  applying  a  medicine  by  inunction,  in  order 
that  the  circulation  of  cutaneous  vessels  may  favor  absorption.  Animal  oils 
are  more  easily  absorbed  by  the  skin  than  vegetable  oils. 

SUMMARY 

The  skin  is  protective,  excretory,  an  organ  of  special  sense,  of  heat 
regulation  and — to  a  moderate  extent— of  absorption. 


CHAPTER  XVII 
MAMMARY  GLANDS.     DUCTLESS  GLANDS 

THE  MAMMARY  GLANDS 

The  mammary  glands  are  placed  between  two  layers  of  super- 
ficial fascia  in  front  of  the  thorax,  occupying  a  space  between  the 
third  and  sixth  ribs,  inclusive.  They  are  covered  by  a  layer  of  adi- 
pose tissue  and  lie  between  two  layers  of  superficial  fascia.  They 


Aerol  a  — A^fe 


FIG.  168. 
Showing  enlarged  milk  ducts  during  lactation. — (Morris.} 

consist  of  little  tubes,  lined  with  milk-secreting  cells  and  grouped 
in  small  lobules,  held  together  by  connective  tissue  imbedded  in 
adipose.  The  lobules  unite  to  form  lobes,  18  or  20,  each  with  its 
own  duct,  thereby  constituting  a  complete  gland  in  itself;  these 
1 8  or  20  milk  ducts  (lactiferous  ducts)  approach  the  nipple  and  open 
at  its  summit.  The  nipple  is  surrounded  by  a  ring  of  darker 
modified  skin  called  the  areola.  A  few  small  elevations  are  seen 
on  the  areola;  they  are  called  the  glands  of  Montgomery. 

260 


COMPOSITION   OF   MILK  261 

Frequently,  prolongations  of  mammary  tissue  extend  laterally  from  the 
gland  toward  the  border  of  the  axilla,  sometimes  they  are  found  near  the 
sternum. 

The  function  of  the  mammary  gland  is  the  secretion  of  milk. 
This  is  a  true  secretion;  the  cells  of  the  tubules  forming  a  new  sub- 
stance from  materials  brought  by  the  blood,  which,  although  not 
utilized  in  the  body  where  it  is  formed,  is  not  only  useful  but 
capable  of  sustaining  life. 

Note. — The  presence  and  activity  of  the  ovaries  seem  to  be  essential  to 
the  proper  development  of  the  mammary  gland. 

Milk  is  a  bluish-white  fluid  consisting  of  clear  plasma  (milk 
plasma)  holding  nutritive  substances  in  solution  and  floating 
myriads  of  oil  globules,  to  which  it  owes  its  white  color.  It  is  a 
natural  emulsion.  The  variety  of  nutritive  substances  contained 
in  it  is  sufficient  for  the  development  of  the  body  of  the  infant. 

Human  milk  is  amphoteric.1 

The  contained  proteins  are  peculiar  to  milk  and  form  a  soft 
flaky  curd  in  the  process  of  digestion.  They  are  several  in  number, 
the  most  important  being  caseinogen,  from  which  casein  is  derived 
in  the  process  of  digestion.  (Cow's  milk  forms  a  tough  curd  in 
digesting.  It  contains  more  casein  but  less  sugar  and  less  fat.  It 
is  nearer  acid  than  human  milk.) 

The  sugar  of  milk  is  lactose  (probably  absorbed  as  such — does 
not  require  digesting).  The  salts  are  the  various  salts  found  in 
foods  and  the  body  tissues,  the  most  abundant  being  compounds 
of  calcium,  potassium  and  sodium. 

The  water  and  salts  are  derived  directly  from  the  blood  by 
filtration;  the  special  proteins  and  lactose  are  secreted  by  the  cells 
of  the  tubules.  (Lactose  is  found  nowhere  but  in  milk,  the  same 
is  true  of  lact-albumin — they  are  special  secretions  of  the  mammary 
glands.) 

Average  percentage  of  fat,  sugar  and  proteins  in  milk  as  given 
by  Holt: 

Colostrum         Human  milk  Cow's  milk 

Fats 2.04 3-5       3.5 

Sugar 3.74 6-7  4.3 

Proteids..  5.71  1-2.25 4 

1  Amphoteric.  Neither  acid  nor  alkaline,  acting  on  both  red  and  blue  litmus 
paper. 


262  ANATOMY   AND    PHYSIOLOGY 

During  pregnancy  the  areola  acquires  a  deeper  color  (which  is 
permanent)  and  the  glands  of  Montgomery  are  enlarged. 

At  this  time  the  blood  supply  of  the  gland  increases,  the  glands 
become  large,  and  changes  occur  in  the  lining  of  the  tubules,  which 
result  in  the  secretion  of  milk.  This  is  perfected  soon  after  the 
end  of  pregnancy. 

The  first  fluid  which  is  drawn  from  the  breast  is  called  colos- 
trum; it  is  yellow  (from  the  presence  of  colostrum  corpuscles), 
alkaline,  rich  in  proteins  and  salts  but  not  in  sugar  nor  in  fat.  '  It 
contains  a  substance  which  acts  as  a  laxative  for  the  infant. 

The  secretion  of  milk  is  influenced  by  the  diet  of  the  mother  and 
may  be  modified  in  both  quantity  and  quality  by  food  selection. 
A  still  greater  effect  is  produced  by  the  condition  of  her  nervous 
systems;  it  is  well  known  that  fright  or  anger,  or  intense  emotion, 
may  so  affect  the  milk  as  to  make  it  injurious  to  the  infant. 
Fatigue,  worry,  loss  of  sleep,  etc.,  are  all  to  be  avoided  by  the 
nursing  mother. 

Human  milk  contains  a  small  quantity  of  starch  splitting 
(amylolytic)  enzyme;  it  is  possible,  therefore,  to  exert  some  effect 
upon  the  starch  content  of  barley  water  in  the  food  of  the  young 
infant  so  that  some  nourishment  may  be  gained  from  it. 

The  milk  may  differ  in  the  two  breasts  of  the  same  person. 

Menstruation  is  accompanied  by  a  diminution  of  lactose  and 
an  increase  of  fat  and  casein. 

The  milk  of  the  pregnant  woman  is  poor  in  quality,  especially 
in  fat. 

Clinical  note. — Certain  drugs  taken  by  the  mother  will  be 
eliminated  through  the  milk  in  sufficient  degree  to  affect  the 
child;  as  beer,  or  bromides,  salines  and  other  cathartics;  strychnia, 
arsenic,  etc. 

Surgical  note. — Mammary  abscess  is  caused  by  infection 
through  a  break  or  fissure  in  the  skin  of  the  nipple,  the  pus  form- 
ing between  the  lobes  of  the  gland.  Post-mammary  abscess  is  in 
the  fascia  behind  the  gland. 

THE  DUCTLESS  GLANDS  OR  THE  ENDOCRIN  SYSTEM 

This  system  includes  the  ductless  glands  and  the  chromaffin 
tissues. 


THE  ^PANCREAS  263 

These  are  the  organs  which  resemble  glands  but  have  no  ducts. 
They  are  supplied  with  sympathetic  nerves,  and  possess  many 
lymphatics  and  blood-vessels;  the  secretions  which  they  produce 
are  internal  secretions  and  are  carried  in  these  vessels.  The  most 
important  ductless  glands  are  the  spleen,  adrenal  bodies  and 
certain  portions  of  the  pancreas,  in  the  abdomen;  thyroid,  para- 
thyroid, and  ^thymus  bodies  in  the  neck;  pituitary  body  (or 
hypophysis)  in  the  cranial  cavity.  To  these  may  be  added  the 
ovaries  (also  the  carotid,  parasympathetic  and  coccygeal  bodies). 

The  cells  of  the  chromaffin  tissues  are  found  in  the  interior  of 
the  adrenal  bodies  and  in  certain  small  groups  which  are  ranged 
along  the  abdoninal  aorta. 

Each  of  the  structures  of  the  endocrin  system  bears  a  relation 
to  one  or  more  of  the  others  which  is  not  yet  perfectly  understood. 

Their  secretions  have  never  been  obtained  for  examination 
but  there  is  abundant  evidence  that  they  exist. 

The  name  autocoid  substances  has  been  proposed  for  the  active 
agents  in  these  secretions.  It  is  believed  that  there  are  two  kinds 
of  autocoid  substances:  the  hormones,  which  stimulate  activity 
in  tissues  to  which  the  blood  carries  them,  and  the  chalones, 
which  inhibit  or  prevent  activity  where  they  are  carried.  Each 
member  of  the  endocrin  system  has  its  own  special  autocoid 
substance. 

So  little  is  understood  of  the  action  of  these  various  organs 
that  descriptions  are  necessarily  brief. 

THE  PANCREAS 

In  addition  to  the  digestive  ferments  of  the  pancreas  it  produces 
another  and  highly  important  substance,  which  either  disposes  of 
sugar  in  the  blood,  or  is  associated  with  the  glycogenic  function  of 
the  liver,  or  both.  This  is  supposed  to  be  the  special  function  of 
groups  of  cells  called  "islands  of  Langerhans"  which  are  embedded 
in  the  substance  of  the  pancreas.  They  resemble  glands  but 
have  no  ducts;  they  are  surrounded  by  a  network  of  capillaries 
and  their  internal  secretion  is  transmitted  by  these  vessels. 

The  blood  supply  to  the  pancreas  is  very  free,  being  derived 
from  the  hepatic,  splenic  and  superior  mesenteric  arteries.  This 
indicates  the  importance  of  the  gland. 


264  ANATOMY  AND   PHYSIOLOGY 

Clinical  notes. — Disease  of  the  pancreas  is  accompanied  by  the  appearance 
of  an  excessive  amount  of  sugar  in  the  urine,  or  diabetes  mellitus  of  a  severe 
character. 

Removal  of  pancreas,  if  complete,  causes  the  same  result  which,  however, 
may  be  prevented  by  transplantation  of  a  piece  of  pancreas  tissue  under  the 
skin. 

THE  SPLEEN 

It  is  believed  (but  not  proven)  that  the  cells  of  the  splenic  pulp 
contain  an  enzyme  which  aids  in  the  digestion  of  protein  foods, 
through  its  action  upon  the  pancreas,  by  furnishing  hormones  to 
stimulate  the  production  of  protein-digesting  enzymes  in  the  pan- 
creatic juice. 

THE  ADRENAL  BODIES 

The  adrenals  (suprarenal  capsules),  are  two  small  gland-like 
bodies  resting  on  the  upper  extremities  of  the  kidneys,  hence  their 
name.  They  are  triangular  in  shape,  yellowish  in  color,  and  have 
many  blood-vessels  and  nerves.  The  superficial  portion  of  the 
adrenal  body  is  the  cortex  or  cortical  portion. 
It  is  this  part  which  is  in  some  way,  neces- 
sary to  life. 

The  interior  portion,  enclosed  by  the 
cortex,  is  the  medulla,  or  medullary  por- 
tion; this  is  one  of  the  chromaffin  tissues, 
and  it  is  thought  that  the  internal  secretion 
is  here  formed.  The  adrenal  bodies  are 
important  organs,  as  it  is  found  that  when 
they  are  removed  death  follows  soon,  but 
their  use  is  not  yet  fully  understood.  It 
has,  however,  been  determined  that  the 
internal  secretion,  epinephrin,  acts  through 
RESTING  UPON  THE  KID-  sympathetic  nerves  on  plain  muscle  fibers 
and  the  heart;  its  effect  is  to  cause  contrac- 
tion of  small  arteries,  thus  increasing  blood  pressure,  at  the  same 
time  slowing  the  rate  of  the  heart  beat.  Because  of  this,  epinephrin 
or  adrenalin  is  an  important  agent  in  checking  hemorrhage  by 
local  application,  as  in  operations  upon  the  throat  or  nose. 

A  solution  of  epinephrin  or  adrenalin  given  by  hypodermic  in- 
jection is  used  to  relax  the  spasm  of  bronchiole  muscle  fiber  in 


THYROID   BODY 

asthma.  It  will  also  shorten  the  coagulation  time  of  blood  (tem- 
porarily). It  inhibits  contraction  of  the  stomach  and  intestine, 
also  of  bladder  and  uterus. 

In  the   disease   called  " bronzing  of  the  skin,"  or  Addison's 
disease,  these  bodies  are  found  to  be  changed. 


THE  THYROID  BODY 

The  thyroid  body  is  situated  in  the  anterior  part  of  the  neck 
(Fig.  170). 

It  has  two  lateral  lobes  lying  close  to  the  upper  portion  of  the 
trachea  and  connected  by  a  middle  portion  called  the  isthmus. 


Median  portion  of  crico- 
thyroid  membrane 

Crico-thyroid  muscle 


Thyroid  isthmus 


Lateral  lobe  of  thyroid  body 


FIG.  170. — THYROID  BODY. — (Morris.} 

These  lobes  are  about  one  and  one-fourth  inches  wide,  and  extend 
about  two  inches  upward  along  the  sides  of  the  larynx.  A  middle 
lobe  may  exist,  extending  upward  from  the  isthmus  in  front  of 
the  larynx. 

The  substance  of  the  thyroid  body  is  made  up  of  closed  sacs 
containing  a  thick  semifluid  substance  (colloid  substance).  They 
are  surrounded  by  many  capillaries;  the  thyroid  arteries  being 
four  in  number,  the  blood  supply  is  very  free.  It  is  supported  in 
its  position  by  fibrous  attachments  to  the  sides  of  the  larynx  and 
also  to  the  fascia  behind  the  trachea. 

Clinical  note. — If  the  thyroid  body  becomes  very  much  enlarged  it  does 
not  freely  glide  upward  and  downward  with  the  larynx  in  the  act  of  swallow- 


266  ANATOMY   AND    PHYSIOLOGY 

ing  as,  normally,  it  should  do;  if  it  is  fixed  by  adhesions  or  by  excessive 
growth  it  exerts  traction  upon  the  larynx  and  trachea  which  is  visible  during 
the  movements  of  swallowing. 

The  function  of  the  thyroid  body  is  important  but  not  well 
explained.  It  is  observed  that  the  development  of  both  mind  and 
body  is  arrested  if  the  thyroid  be  absent,  or  if  it  does  not  itself 
develop  in  childhood;  this  condition  is  known  as  cretinism. 

Degeneration  or  complete  removal,  in  adult  life,  is  followed  by 
excessive  growth  (but  imperfect  development)  of  connective  tissue 
and  skin  elements,  or  myxedema,  and  a  gradual  deterioration  of 
mental  power.  These  effects  may  be  prevented  by  leaving  a 
small  portion  of  the  gland  in  place  or  by  transplanting  it. 
.  From  these  and  other  clinical  observations  it  is  evident  that 
the  internal  secretion  of  this  body  exercises  an  important  influence 
upon  nutrition.  It  stimulates  cardiac  action,  increases  blood 
pressure,  and  restrains  a  tendency  to  obesity. 

Clinical  notes. — Simple  enlargement  of  the  thyroid  body  constitutes 
goiter,  which  is  said  to  be  frequent  in  certain  countries  where  the  drinking 
water  contains  much  lime. 

Exophthalmic  goiter  is  a  diseased  condition  of  the  thyroid  body  with  the 
following  symptoms:  Enlargement  and  pulsation  of  the  thyroid,  rapid  heart 
action,  tremor,  and  protrusion  of  the  eyeballs. 

THE  PARATHYROID  BODIES 

The  parathyroid  bodies  are  small  bodies  situated  above  and 
laterally  to  the  thyroid,  two  on  each  side.  They  have  an  abundant 
blood  supply.  Their  function  is  not  explained  but  it  is  now  known 
that  their  removal  is  soon  followed  by  convulsive  affections, 
tremor,  etc.,  suggesting  the  presence  of  an  irritant  in  the  blood 
which  did  not  exist  before.  Consequently  it  may  be  that  their 
internal  secretion  is  able  to  neutralize  certain  toxic  substances 
formed  elsewhere,  and  capable  of  causing  death. 

Both  parathyroid  and  thyroid  bodies  contain  iodin  in  combina- 
tion with  some  other  substance. 

THE  THYMUS  BODY 

The  thymus  body  (Fig.  171)  is  an  organ  of  fetal  and  infantile 
life,  situated  below  the  thyroid,  being  mostly  in  the  thorax  and  ex- 


PITUITARY   BODY 


267 


tending  downward  to  the  pericardium.  It  is  two  and  one-half 
inches  Jong  at  the  age  of  two-  years,  but  dwindles  slowly  from  that 
time  on,  leaving  very  perceptible  remnants  only,  during  adult 
life.  A  persistent  thymus  is  one  of  the  features  of  the  condition 
known  as  infantilism.  It  has  been  thought  that  its  secretion 
lowers  blood  pressure. 


Thyroid 


Small  intestine 


Bladder 


Trachea 


-  Thymus 


Lung 

Right  auricle 

Right  ventricle 


Stomach 

Part  of  transverse 
colon 


Hypogastric 
artery 


FIG.  171. — VISCERA  AT  BIRTH.  NOTE  THE  THYMUS  BODY,  THE  SIZE  OF  THE 
LIVER  AND  THE  LOCATION  or  THE  BLADDER  AND  THE  HYPOGASTRIC  ARTERIES. — 
(Morris  after  Rudinger.) 


THE  PITUITARY  BODY 

The  pituitary  body  (Fig.  193)  (hypophysis  cerebri)  is  included 
among  ductless  glands.  It  rests  in  the  sella  turcica  of  the  sphenoid 
bone.  By  investigation  it  has  been  learned  that  degeneration  of  this 
body  in  the  adult  is  the  probable  cause  of  the  disease  called  acro- 
megaly,  which  is  characterized  by  an  overgrowth  or  hypertrophy 
of  the  bones  of  the  face  and  extremities.  Should  this  occur  in 
young  children  or  while  the  bones  are  still  developing,  over-growth 
of  the  skeleton  or  gigantism  will  result.  Certain  conclusions  have 


268  ANATOMY   AND   PHYSIOLOGY 

been  founded  upon  this  association,  presupposing  that  it  produces 
an  internal  secretion  which  regulates  the  growth  of  bones.  It  also 
increases  the  force  of  cardiac  action  and  general  blood  pressure. 
It  is  found  to  stimulate  the  contraction  of  unstriped  muscle  fiber, 
as  in  the  uterus,  and  has  been  used  for  that  purpose.  Its  influence 
upon  metabolism  is  still  under  investigation.  Its  removal  is  fol- 
lowed by  atrophy  of  the  generative  organs. 

Clinical  note. — Hypertrophy  or  tumor  of  the  pituitary  body 
or  hypophysis  causes  blindness  by  pressure  upon  optic  nerve  fibers. 

The  carotid  bodies  are  placed  behind  the  common  carotid  artery  just  at 
the  point  where  it  bifurcates.  Use  unknown.  The  para-sympathetic  bodies 
one  to  four  in  number,  lie  in  front  of  the  third  and  fourth  lumbar  vertebrae. 
Use  unknown.  The  coccygeal  body  lies  in  front  of  the  lowest  part  of  the 
coccyx.  Use  unknown. 


CHAPTER   XVIII 
METABOLISM 

We  have  now  studied  the  various  organs  which  form  secretions, 
or  substances  which  may  be  either  devoted  to  a  special  use  in  the 
body,  or  expelled  as  of  no  further  use.  These  latter  are  known  as 
excretions. 

SECRETION 

Following,  is  an  enumeration  by  way  of  review,  of  the  principal 
organs  whose  secretions  are  used  in  the  body,  with  a  partial  list  of 
their  functions: 

First. — The  epithelial  cells  of  all  surface  membranes  and  cavities 
should  be  included: 

Those  of  mucous  membranes,  secreting  mucus. 

Those  of  serous  membranes,  secreting  serum  (as  in  the  pleural, 
pericardial  and  peritoneal  cavities,  and  the  subdural  and  sub- 
arachnoid  spaces  of  brain  and  spinal  cord). 

Those  of  synovial  membranes,  secreting  synovia. 
The  secreting  cells  of  glands  come  next. 

The  salivary,  gastric  and  intestinal  glands  and  pancreas  secrete 
saliva,  gastric,  intestinal  and  pancreatic  juices. 

The  liver  secretes  bile  (and  forms  glycogen). 

The  mammary  glands  secrete  milk. 

The  lacrimal  glands  secrete  tears. 

The  sebaceous  glands  secrete  sebum. 
Of  the  secretions  of  so-called  ductless  glands,  or  endocrin  system. 

That  of  the  pancreas  influences  glycogen-processes  in  the  liver. 

That  of  the  adrenal  bodies  increases  blood  pressure  (contracting 
arterioles)  and  retards  the  rate  of  cardiac  action,  also  favors  the 
formation  of  sugar  in  the  body. 

That  of  the  thyroid  body  influences  tissue  metabolism,  increases 
cardiac  action,  and  diminishes  obesity. 

That  of  the  parathyroids  destroys  toxins  in  the  blood  (or 
inhibits  their  formation?). 

269 


270  ANATOMY   AND   PHYSIOLOGY 

That  of  the  pituitary  body  (or  hypophysis)  restrains  growth  of 
osseous  tissue  and  influences  metabolism,  establishing  a  tolerance 
for  sugars. 

That  of  the  ovary  is  associated  with  the  function  of  the  mam- 
mary gland  and  the  uterus,  and  influences  the  action  of  vaso- 
motor  nerves  of  the  systemic  circulation.  This  internal  secretion 
is  furnished  by  the  corpus  luteum  (p.  349). 

In  addition  to  the  above  may  be  mentioned: 

The  spleen  and  lymph  glands  which  supply  white  cells  to  blood 

The  marrow  of  bones  which  supply  red  cells  to  blood. 

The  testes  which  produce  spermatozoa. 

The  secretions  of  the  organs  named,  serve  various  purposes, 
aiding  or  influencing  nutrition,  or  assisting  in  the  formation  of 
other  substances. 

EXCRETION 

Excretions. — These  are  the  substances  which  must  be  elimi- 
nated from  the  body. 

All  tissue  action  uses  up  some  material,  leaving  a  varying  rem- 
nant of  waste  matter  which  cannot  be  utilized — like  the  ashes  from 
a  fire.  These  wastes  appear  either  dissolved  in  water  as  urine  and 
perspiration,  or  in  the  form  of  gas  or  vapor. 

Tissue  waste  may  be  reduced  ultimately  to  comparatively  few 
substances,  the  most  important  being  urea,  carbon  dioxide,  various 
salts  and  water.  Urea  is  most  abundant  in  urine,  C02  in  exhaled 
air,  and  all  of  these  in  small  quantity  in  perspiration. 

Therefore,  the  organs  of  elimination  are: 

The  kidneys,  which  excrete  urine. 

The  skin,  which  excretes  perspiration. 

The  lungs,  which  exhale  carbon  dioxide,  organic  matters,  am- 
monia and  water. 

To  these  may  be  added  the  liver  and  the  intestinal  canal. 

The  liver  excretes  waste  matters  with  the  bile  and  forms  urea. 

The  intestinal  canal  .excretes  small  quantities  of  tissue  waste 
(gases,  water,  mucus,  etc.). 

GENERAL  METABOLISM 

We  have  studied  the  framework  of  the  body  with  its  various 
connections  and  adaptations,  its  coverings  and  its  cavities,  the 


METABOLIC  PROCESSES  271 

organs  by  which  it  is  fed  and  the  wear  and  tear  of  its  machinery 
continually  made  good,  as  it  is  nourished  and  sustained — a 
living  organism. 

The  combined  processes  of  up-building  and  breaking  down — in 
the  living  body — constitute  metabolism.  A  well-equipped  labora- 
tory presents  facilities  for  illustrating  the  actual  chemical  changes 
which  take  place,  but  only  in  the  living  cell  are  they  metabolic. 

Attention  has  been  directed  to  the  four  classes  of  substances 
composing  the  body  tissues,  and  the  corresponding  food-substances 
supplied  to  them  in  the  dietary.  We  have  seen  that  these  foods 
are  presented  to  the  body  in  compounds  more  or  less  complex  (most 
of  them  insoluble)  and  we  have  traced  (briefly)  their  changes  in  the 
system  from  the  time  of  ingestion  to  their  disposition  in  the 
tissues  or  their  expulsion  as  excreta.  It  remains  to  review  them 
from  the  standpoint  of  their  value  in  metabolism. 

All  foods  must  subserve  one  or  more  of  three  purposes,  namely: 
—to  evolve  heat;  to  release  energy ;  to  repair  waste. 

Proteins,  being  reduced  by  digestion  to  simpler  forms  (peptones 
and  amino-acids)  are  absorbed  and  appear  reconstructed  in  muscles, 
blood,  lymph  and  milk,  mainly  (in  all  tissues  actually),  where  by 
their  nitrogenous  portion  they  contribute  to  the  "  betterment  of 
cell  conditions''  and  compensate  for  wear  and  tear  everywhere  in 
the  body;  by  their  non-nitrogenous  elements  they  evolve  heat 
and  create  energy. 

Protein  wastes  (or  excreta)  take  the  form  of  urea — uric  acid  and 
compounds — ammonia — excreted  through  the  kidneys. 

Carbohydrates,  taken  as  sugar  or  converted  into  that  form, 
are  absorbed  and  circulated,  stored  in  liver  and  muscle  as  glycogen 
to  appear  when  needed  as  sugar  again — to  be  oxidized  for  the  pro- 
duction of  heat  and  energy  or  stored  as  fat.  Their  excreta  are  CO2 
and  water. 

Fats,  after  digestion,  are  distributed  for  use  in  many  parts, 
their  oxidations  evolving  heat  and  motion,  or  are  stored  in  sub- 
cutaneous fascia,  marrow,  between  viscera,  etc.  Their  excreta 
are  CO2  and  water. 

Mineral  Salts  and  water  are  absorbed  together  in  solution  and 
distributed  to  aid  in  the  formation  of  various  tissues  throughout 
the  body. 

It  thus  appears  that  all  foods  contribute  to  body  heat  and 


272  ANATOMY  AND   PHYSIOLOGY 

energy,  by  entering  into  the  up-building  of  the  tissues  which  are 
quickly  used  up  for  those  purposes ;  while  the  proteins  have  in  addi- 
tion as  their  principal  function,  the  construction  of  body  tissues  of  a 
more  permanent  character. 

These  changes  are  largely  dependent  upon  the  combination  of 
oxygen  with  food  or  tissue  compounds.  "The  essential  source 
of  heat  and  mechanical  work  developed  in  the  animal  organism 
is  to  be  found  in  the  oxidations"  (Hammarsten).  But  behind 
these  are  the  enzymes;  in  nearly  all  active  tissue  cells  the  changes 
begin  with  their  action.  Certain  oxidizing  ferments  make  the 
first  splitting  of  complex  substances,  afterward  the  union  with 
oxygen  follows. 

In  digestion  processes  we  have  seen  that  the  first  change  is 
associated  with  a  splitting  of  and  union  with  the  elements  of  water 
(H20).  The  enzymes  which  set  this  change  in  motion  are  hydro- 
lytic  enzymes. 

FOOD  VALUES 

By  study  and  experiment  it  is  found  that  the  proper  propor- 
tions of  proteins,  carbohydrates  and  fats  in  the  human  dietary  are 
as  follows: — proteins  one-fifth,  fats  one-fifth,  carbohydrates 
three-fifths.  Since  in  the  body,  heat  and  mechanical  work  are 
produced  in  company,  the  degree  of  heat  evolved  by  work  is  taken 
as  the  measure  of  force  to  be  supplied  by  food,  or  the  measures  of 
food  value. 

The  heat  unit  of  measurement  is  called  the  calorie  (large 
calorie),  which  signifies  the  amount  of  heat  required  to  raise  one 
kilo  of  water  to  i°C. 

A  food  which  when  burned  will  do  this  has  a  calorific  value  of 
one  degree,  that  is,  it  is  graded  at  one  calorie  in  value. 

The  following  are  estimated  averages  of  calorific  values. 

Proteins one  gram  yields  4 .    to  4.  i  calories. 

Carbohydrates one  gram  yields  4.1  calories. 

Fat one  gram  yields  9 . 3  calories. 

The  average  working  man  of  20  kilos  weight,  needs  a  ration  of  30-40 
calories  for  each  kilo. 

The  average  resting  man  of  20  kilos  weight,  needs  30  cal.  per  kilo. 
The  average  sleeping  man  of  20  kilos  weight,  needs  25  cal.  per  kilo. 

Upon  the  basis  of  calorific  values  various  diet  tables  have  been 


FOOD  VALUES 


273 


made,  by  the  use  of  which  the  needs  of  individual  patients  can  be 
met.  The  following,  for  typhoid  patients  (enteric  fever),  is 
selected  from  a  set  of  such  diet  charts  prepared  by  Dr.  Frances 
C.  Van  Gasken  and  Dr.  Mary  P.  Rupert  for  use  in  the  Woman's 
Hospital  of  Philadelphia. 

TABLE  A 


Portion. 

Food. 

P. 

F. 

C. 

Calories. 

•2  nints 

Milk  (whole)  . 

c;i 

e  4 

66 

Q7C 

i  pint.  . 

Meat  broth  

20 

.5 

89 

? 

EgKS.  .  , 

24 

16.5 

24O 

i  nint 

Lemon  or  orange  jelly.  . 

8  5 

12  .  <; 

72 

3  oz 

JMilk  sugars 

I    r 

7? 

2Jtf 

103 

71 

143-5 

I696 

TABLE  B 


Admissible. 

Grams. 

p. 

F. 

C. 

Approxi- 
mately 
200  C. 

8  oz 

Gruel  (with  milk) 

(200) 

4 

4 

12 

« 

2  tablespoons 

Rice  well  cooked 

(r0) 

2 

•JQ 

it 

4.  oz  . 

Junket  4~  sugar  

(31) 

, 

II 

tt 

•?  oz 

Custard 

(80) 

r 

2 

IO 

n 

2  tabelspoons  .  .  . 

Ice  cream  

(25) 

1 

7 

9 

n 

I  OZ    . 

Cocoa  

(25) 

C 

7.  c 

t( 

Cognac 

2C 

« 

Black  coffee  

225  c.c. 

,. 

From  Table  B,  articles  may  be  selected  at  discretion.  The 
total  calorific  value  of  food  for  each  twenty-four  hours  should 
reach  the  following  averages : 


Febrile 
period 


Proteids. . .  .     300  cal. 

Fats 405  cal.   Convales- 


Carbohy- 
drates i>3oo  cal. 


cent  period 


Proteids. . .  .     480  cal. 

Fats 540  cal. 

Carbohy- 
drates    1,260  cal. 


Total 2,005  cal. 


Total 2, 280  cal. 


274  ANATOMY  AND   PHYSIOLOGY 

Animal  Heat. — An  internal  temperature  of  about  100°  F.  is 
necessary  to  the  normal  activity  of  the  body  tissues.  This,  the 
tissues  themselves  can  accomplish  with  proper  materials  in  the 
form  of  food,  and  oxygen  for  the  chemical  work,  the  latter  being 
supplied  in  the  air  we  breathe. 

The  great  source  of  animal  heat  is  in  the  most  active  tissues— 
muscles  and  glands;  the  heat  produced  in  these  is  equalized  in 
all  tissues  by  the  circulating  fluids. 

The  kind  of  food  which  is  eaten  has  a  direct  effect  upon  the 
production  of  heat;  protein  substances  yield  more  than  starchy 
foods,  while  fats  yield  more  than  proteins  and  starches  together. 

The  ingestion  of  food  causes  a  rise  of  temperature,  due  both  to 
the  chemical  and  mechanical  work  of  the  digestive  organs.  This 
rise  is  normal. 

As  the  body  is  continually  generating  heat  so  it  is  continually 
losing  it  in  various  ways — by  radiation  to  the  surrounding  atmos- 
phere, by  conduction  to  the  clothing,  by  evaporation  from  the 
lungs  and  skin,  etc.,  etc. 

In  cold  weather  heat  production  is  desired.  This  can  be  accom- 
plished by  selecting  heat-generating  foods,  by  taking  hot  foods  and 
by  muscle  exercise;  the  heat  thus  generated  can  be  conserved  by 
clothing  the  body  in  materials  which  prevent  radiation  and  con- 
duction, as  wool  or  silk.  In  hot  weather  heat  production  is  to  be 
avoided  and  heat  dissipation  is  sought;  this  is  facilitated  by  the 
selection  of  starchy  and  protein  foods,  taking  cool  drinks  and  wear- 
ing lighter  garments,  as  cotton  or  linen. 

For. health  and  comfort  it  is  necessary  that  a  proper*  internal 
relation  be  maintained  between  heat  production  and  heat  dissipation. 
For  this,  the  body  possesses  its  own  self-regulating  mechanisms; 
for  example,  muscle  exercise  produces  heat,  but  the  associated 
activity  of  the  sweat  glands  so  favors  heat  escape,  that  the  injuri- 
ous effect  of  excessive  body  heat  is  prevented.  Again,  the  viscera 
concerned  in  digestion  (notably  the  liver)  generate  much  heat;  by 
the  blood  it  is  carried  to  the  cooler  extremities. 

A  high  temperature  of  the  surrounding  atmosphere  so  affects 
the  nerve  centers,  that  the  respiratory  function  is  stimulated 
and  evaporation  from  the  lungs  increased,  at  the  same  time 
activity  of  the  skin  is  very  marked  and  evaporation  of  perspiration 
follows. 


RANGE   OF   TEMPERATURE  275 

These  natural  processes  of  mutual  accommodation  result  in 
preserving  a  necessary  uniform  temperature  of  the  body,  which 
makes  it  independent,  within  reasonable  limits,  of  external  sur- 
roundings. The  normal  temperature,  98.4°  F.,  is  maintained  so 
long  as  the  proper  balance  is  preserved  between  heat  production 
and  heat  escape.  Elevation  of  temperature  is  caused  when  produc- 
tion is  too  rapid  or  dissipation  is  too  slow.  Very  high  temperature 
indicates  excessive  metabolism  and  impaired  dissipation.  (Another 
result  of  excessive  metabolism  is  seen  in  the  wasting  of  the  body  in 
fevers,  as  typhoid  fever.) 

Subnormal  temperature  indicates  diminished  tissue  change  or 
metabolism,  suggesting  impairment  of  vitality.  (A  temperature 
of  77°  F.  is  followed  by  death,  as  cell  activity  cannot  go  on  in  a 
temperature  so  low.) 

Range  of  normal  temperature. — The  normal  adult  tempera- 
ture is  98 . 4°  F.  in  the  axilla,  in  the  mouth  slightly  higher.  It  is  a 
degree  higher  in  the  rectum. 

During  early  life  when  metabolism  is  active  it  is  slightly  higher 
than  in  later  years.  In  old  age  it  is  often  a  degree  higher  than  in 
middle  life. 

A  difference  of  a  degree  is  noted,  in  health,  between  the  tem- 
perature of  early  morning  and  evening,  for  example,  at  5  A.  M.  and 

5  P-  M- 

Average  range  of  body  temperature  for  different  ages : 

In  infancy 99~99  •  5 

At  puberty 99 

In  adult  life: 

Axillary 98 . 4 

Oral 98.8 

Rectal 99 . 2 

Practical  Conclusions  and  Clinical  Notes 

The  temperature  of  a  patient  should  be  taken  before  a  meal, 
or  after  digestion,  not  during  it. 

In  cold  weather  hot  foods  containing  fats  are  appropriate  for 
the  generation  of  heat;  in  hot  weather  starchy  foods  and  cool 
drinks  are  in  order. 

Alcohol  causes  a  temporary  sense  of  warmth  by  quickening  the 
circulation,  but  this  is  followed  by  dilation  of  the  surface  capillaries 


276  ANATOMY  AND   PHYSIOLOGY 

and  a  consequent  radiation  of  heat.  The  use  of  alcohol  before 
exposure  to  a  low  temperature  should  be  avoided,  unless  some  very 
reliable  measure  is  taken  for  preventing  surface  radiation. 

Muscle  exercise  is  accompanied  by  dilation  of  surface  vessels 
and  escape  of  heat;  this  continues  for  some  time  after  the  exercise 
has  ceased,  therefore,  care  should  be  taken  to  guard  against  too 
great  loss  of  heat  and  a  consequent  "cold"  due  to  chilling  of  the 
surface,  especially  when  exposed  to  a  draft  of  air. 

The  fact  that  the  body  loses  heat  rapidly  by  conduction,  should 
warn  the  nurse  against  putting  cold  garments  on  a  delicate  patient, 
and  especially  against  placing  a  patient  in  a  cold  bed.  Remember 
that  the  body  of  the  patient  must  furnish  the  heat  to  warm  the  bed 
and  this  makes  an  unnecessary  demand  upon  vitality  already 
impaired  by  illness. 

Small  animals  need  more  heat  relatively  than  large  ones 
because  their  surface  is  greater  in  proportion  to  their  bulk,  conse- 
quently they  radiate  more  heat.  During  the  first  three  days  of 
the  infant's  life  its  metabolism  falls;  it  then  begins  to  rise  and 
reaches  the  normal  average  for  its  size  after  about  two  weeks. 

Practical  point.- — Wrap  the  new-born  child  and  the  young  infant 
more  warmly  than  it  seems  to  need.  Remember  that  it  is  not 
yet  able  to  manufacture  sufficient  heat  to  keep  it  comfortable. 

Influence  of  work  upon  metabolism — it  accelerates  the  proc- 
esses, with  increased  consumption  of  oxygen  and  elimination  of 
carbon  dioxide. 

Influence  of  light — similar  in  effect  (although  slight  in  degree) 
because  light  stimulates  muscle  and  tissue  tone. 

Influence  of  darkness — It  retards  metabolism  from  absence  of 
surface  stimuli. 


CHAPTER  XIX 
THE  NERVE  SYSTEM 

CEREBRO-SPINAL   AND    SYMPATHETIC   DIVISIONS, 
NERVE  TISSUES  AND  THE  SPINAL  CORD 

The  preceding  chapters  have  been  devoted  to  the  study  of 
many  organs  grouped  into  systems  for  different  purposes.  Of 
some  we  can  say  that  their  functions  are  exercised  consciously 
and  under  voluntary  control;  others  are  so  exercised  to  a  partial 
extent  only;  as  the  muscles  of  the  extremities  and  those  of  respira- 
tion. Still  others  are  absolutely  beyond  our  control — as  the  heart, 
the  stomach  and  intestine,  and  others.  We  are,  therefore,  pre- 
pared to  find  in  the  nerve  centers  of  the  body,  a  wonderful  plan 
for  providing  nerve  force  that  shall  stimulate  the  activities  of 
these  widely  differing  organs,  and  at  the  same  time  bring  them 
into  one  harmonious  whole. 

The  body  functions  are  classified  as  voluntary  and  involuntary, 
so  the  nerve  system  is  arranged  in  two  divisions— belonging 
respectively  to  voluntary  and  involuntary  processes,  the  first 
being  called  the  cerebro- spinal  division; the  second,  the  sympathetic 
division. 

NERVE  TISSUES 

The  foundation  cells  of  which  nerve  tissues  are  composed  are 
microscopic  in  size  and  called  neurons.  A  neuron  consists  of  a 
nucleated  cell  body,  an  axon,  and  terminal  divisions. 

The  cell  body  has  short  branches  called  dendrites,  one  of  which 
(sometimes  two)  grows  -longer  to  form  the  axon  or  axis  cylinder 
which  becomes  a  nerve  fiber. 

Note. — The  term  nerve  cell  is  often  used  to  signify  the  cell  body  of  a 
neuron. 

When  the  axon  is  invested  with  a  sheath,  or  medulla,  it  is  a 
medullated  nerve  fiber,  and  such  are  found  in  voluntary  muscles 
and  all  sensitive  parts  of  the  body.  Axons  without  sheaths  are 

277 


278 


ANATOMY   AND   PHYSIOLOGY 


known  as  non-medullated  nerve  fibers,  and  such  are  found  in  in- 
voluntary muscles  and  in  the  walls  of  internal  organs. 

Structures  composing  a  medullated  nerve  fiber: 

1 .  The  axon  or  axis-cylinder. 

2.  Medulla  or  myelin  (white  substance  of  Schwann). 

3.  Neurilemma,  a  transparent  membrane  inclosing  the  myelin  (sometimes 
absent). 


Dendrites     


Nerve  cell 


Axon  - 


A  medul- 
lated fiber 


Medullated 
•     fiber 


Nerve  cell 


FIG.  172. 

FIGS.  167,  168.— NERVE  CELLS.- 


FIG.  173- 
-(Brubaker.} 


Structures  composing  a  non-medullated  nerve  fiber: 

1.  The  axon  or  axis-cylinder. 

2.  Neurilemma  (sometimes  absent). 

Medullated  nerves  are  found  in  voluntary  muscles,  skin,  mucous  and  serous 
membranes,  joints  and  special  sense  organs.  They  constitute  the  main 
portion  of  the  Cerebro-spinal  Division. 

Non-medullated  nerves  are  found  in  glands,  vessels,  hollow  viscera,  and 
muscle  fibers  at  roots  of  hairs.  They  constitute  the  main  portion  of  the 
Sympathetic  Division. 

The  axons  or  nerve  fibers  terminate  in  fine  branches,  which 
connect  them  either  with  various  organs  or  with  the  dendrites  of 
other  cell  bodies,  as  the  case  may  be. 

For  want  of  more  accurate  language,  we  say  that  impulses  are 


NERVES  AND  NERVE  CENTERS  279 

transmitted  through  fibers  either  to  or  from  cell  bodies.  If  to  the  body, 
the  fiber  and  cell  constitute  an  afferent  neuron  (afferent,  bearing 
toward);  if  from  the  cell  body  the  neuron  is  efferent  (efferent,  bearing 
away) .  Afferent  nerves  are  centripetal;  efferent  nerves  are  centrifugal. 

Important  to  remember. — The  cell  body  is  necessary  to  the  life 
of  the  fiber;  if  separated  from  the  cell  body  the  fiber  will  die. 

The  distinguishing  characteristics  of  nerve  tissue  are  sensitive- 
ness or  irritability  and  conductivity. 

THE    CEREBRO-SPINAL    DIVISION    OF    THE    NERVE 

SYSTEM 

The  brain  and  spinal  cord  with  their  nerves  constitute  the 
cerebro-spinal  system,  and  since  the  brain  and  cord  contain  the 
largest  and  most  important  centers,  this  is  often  called  the  central 
nerve  system  (Fig.  174). 

Nerve  tissues  in  the  cerebro-spinal  system  appear  to  the  eye 
as  of  two  kinds,  gray  and  white.  The  gray  tissue,  commonly  called 
"gray  matter,"  is  composed  of  cell  bodies  and  their  branches.  The 
so-called  "  white  matter"  is  composed  of  medullated fibers  belonging 
to  the  cells. 

A  nerve  (of  the  cerebro-spinal  system)  consists  of  many  fibers 
bound  together;  it  resembles  in  appearance  a  white  cord  and  may 
be  so  small  as  to  be  distinguished  with  difficulty,  or  as  large  as  a 
child's  finger — like  the  great  sciatic  nerve. 

A  nerve  is  constructed  after  the  same  plan  as  that  of  a  muscle.  A  connect- 
ive tissue  sheath,  (epi-neurium)  sends  partitions  (peri-neurium)  between 
bundles  of  fibers,  and  a  delicate  membrane  (endo-neurium)  surrounds  each 
fiber. 

Nerves  divide  into  branches  which  may  interlace  with  others  or  join  them 
in  a  common  sheath,  but  no  fiber  ever  unites  with  another.  Each  one  con- 
tinues throughout  the  length  of  the  nerve  of  which  it  forms  a  part. 

Nerve  centers  are  the  gray  cell  bodies  to  which  nerves  belong, 
and  which  are  necessary  to  the  life  of  the  fibers. 

This  term  is  commonly  used  to  signify  a  collection  of  cells 
whose  fibers  form  nerves  having  a  special  function,  or  which  pre- 
side over  a  group  of  movements.  (A  definite  collection  of  gray 
cells  is  also  called  a  ganglion.)  Motor  nerves  transmit  motor 
impulses  from  centers  to  muscles,  while  sensory  nerves  transmit 

1  For  description  of  the  Sympathetic  Division  see  page  316. 


280 


ANATOMY  AND   PHYSIOLOGY 


impressions  from  the  various  parts  of  the  body  to  the  centers  which 
receive  them.  We  commonly  speak  of  motor  nerves  as  running 
down,  and  sensory  nerves  as  running  up,  referring  them  to  the 
spinal  cord  or  brain. 

THE  SPINAL  CORD 

The  spinal  cord  lies  within  the  spinal  canal  in  the  spinal 
column,  being  continuous  with  the  brain.  It  is  a  round  white 
structure  about  seventeen  inches  long,  ex- 
tending from  the  atlas  to  the  second  lum- 
bar vertebra,  where  it  ends  in  a  slender  ter- 
minal filament  which  continues  to  the  end 
of  the  canal.  The  thickness  is  about  half 
an  inch,  being  greater  in  the  lower  cervical 
and  lower  dorsal  regions,  making  the  cervical 
and  lumbar  enlargements  where  nerves  are 
given  off  for  the  extremities.  It  presents 
a  median  fissure  in  front  and  another  at  the 
back,  marking  off  its  right  and  left  halves. 
Other  fissures  divide  each  half  into  anterior, 
lateral,  and  posterior  columns  or  tracts. 

A  transverse  section  will  show  that  the 
interior  of  the  cord  is  grayish  in  color  in- 
stead of  white,  and  this  portion  is  largely 
made  up  of  the  gray  cell  bodies  and  their 
branches,  arranged  in  masses  which  are  con- 
tinuous throughout  the  length  of  the  cord. 

The  section  will  also  show  that  the  area 
occupied  by  the  gray  portion  roughly  re- 
sembles two  crescents  (one  in  either  side), 
connected  together  across  the  middle.  The 
extremities  of  the  crescents  are  called  the 
anterior  and  posterior  horns. 

A  canal,  called  the  central  canal,  runs 
through  the  center  of  the  gray  portion.  It 
may  be  traced  throughout  the  length  of  the  cord  but  is  easily  seen 
only  in  the  upper  part.  It  contains  cerebrospinal  fluid. 

The  white  portion  consists  of  the  bundles  or  tracts  of  the  cord 
(often  called  columns,  the  name  tract  being  applied  to  divisions  of 


FIG.  174.— THE  BRAIN 
AND  SPINAL  CORD. — 
(Quain,  after  Bourgery.) 


THE   DURA  MATER 


28l 


the  columns) .  There  is  a  general  division  into  three  in  each  half— 
the  anterior,  lateral,  and  posterior  tracts.  The  fibers  in  the  anterior 
and  a  portion  of  the  lateral  tracts  are  connected  with  the  cells  of 
the  anterior  horn.  They  conduct  motor  impulses.  The  fibers  in 
the  posterior  and  a  portion  of  the  lateral 
tracts  are  connected  with  the  posterior 
horn,  and  conduct  sensory  impressions. 

All  three  columns  contain  associating  A 
fibers  which  connect  different  parts  of  the 
cord  with   each    other.     These    are    im- 
portant. 

MEMBRANES  OF  THE  SPINAL  CORD 

The  pia  mater. — A  delicate  membrane 
which  bears  the  blood-vessels  and  is  very 
closely  applied  to  the  surface  of  the  cord 
(the  vascular  membrane  of  the  cord). 

The  arachnoid  (web-like). — Outside  of 
the  pia  mater,  this  has  been  classed  among 
serous  membranes  because  its  epithelium 
secretes  a  fluid  like  serum;  it  is  a  single 
fibro-serous  sheet  of  membrane  (not  a 
closed  sac)  which  surrounds  the  cord 
loosely.  The  fluid  within  it  (cerebro-spi- 
nal  fluid)  protects  the  cord  from  friction 
and  vibrations. 

The    dura    mater. — A    strong    white 
fibrous  membrane,  tubular  in   shape,  in    ! 
which  the  cord  is  loosely  suspended.     It  is  attached  above  to  the 
margin  of  the  foramen  magnum. 

The  space  between  the  dura  and  the  arachnoid  is  the  subdural 
space;  that  between  the  arachnoid  and  pia  is  the  subarachnoid 
space;  they  contain  cerebro-spinal  fluid.  The  subarachnoid  space 
is  largest  in  the  lower  portion.  (The  fluid  in  this  space  mixes  with 
that  of  the  central  canal  through  a  small  opening  in  the  pia,  at  the 
base  of  the  brain.) 

The  membranes  are  also  called  the  meninges,  and  their  blood- 
vessels are  the  meningeal  vessels.  Spinal  meningitis  is  inflamma- 
tion of  the  meninges  of  the  cord. 


FIG.  175. — THREE  SECTIONS 

OF  SPINAL  CORD. 
A,   Cervical  region;    B, 
thoracic  region;  C,  lumbar 
region;  p,  posterior  horn;  a, 


282 


ANATOMY   AND   PHYSIOLOGY 


Surgical  note. — The  operation  of  lumbar  puncture  is  for  the  purpose  of 
opening  the  dura  and  arachnoid  and  drawing  off  a  certain  quantity  of 
cerebrospinal  fluid. 

SPINAL  NERVES 

A  spinal  nerve  is  a  collection  of 
motor  and  sensory  fibers  connected 
with  the  spinal  cord  by  two  roots — an 
anterior  root  running  from  the  motor 
cells  and  tracts  and  a  posterior  root 
running  to  the  sensory  tracts  and  cells. 

The  two  roots  become  imbedded 
in  one  sheath  at  the  intervertebral 
foramen  which  transmits  the  nerve 
from  the  spinal  canal. 

Note. — The  "ganglion  of  the  root"  is  a 
small  ganglion  on  the  posterior  root  where  the 
true  root  fibers  arise. 

The  ganglion  contains  the  cell-bodies  of 
fibers  in  the  posterior  roots;  they  are  neces- 
sary to  the  life  of  these  roots.  Two  axons 
belong  to  each  ganglion  cell;  one  becomes 
part  of  a  spinal  nerve  and  ends  in  a  sensitive 
part  of  the  body  (skin,  mucous  membrane, 
muscle  tissue  and  lining  of  joints) ;  the  other 
forms  a  fiber  of  the  posterior  root  of  the  same 
spinal  nerve,  and  enters  the  cord  to  become 
associated  with  cells  of  both  posterior  and 


FIG.  177. — MEMBRANES  OF  SPI- 
NAL CORD. 

i,  Dura  mater;  2,  arachnoid; 
3,  post,  root  of  nerve;  4,  ant. 
root  'of  nerve,  divided;  5,  pia 
mater;  6,  linea  splendens. — 
(Morris,  after  Ellis.} 


anterior  horns.     (The  fibers  of  the  anterior  roots  arise  in  the  cells  of  the  anterior 
horns.) 

Clinical  note. — Since  the  spinal  nerves  contain  both  motor  and  sensory 
fibers,  they  are  called  mixed  nerves;  and  since  the  antero-lateral  divisions  of 
the  cord  are  motor  tracts,  and  the  postero-lateral  divisions  are  sensory 
tracts,  we  can  understand  how  injury  in  one  region  will  cause  paralysis  of 
motion,  and  injury  in  the  other  will  cause  paralysis  of  sensation;  while  injury 
of  a  mixed  nerve  will  cause  loss  of  both  motion  and  sensation  in  the  parts  to 
which  the  nerve  belongs. 

The  next  chapter  will  present  the  spinal  nerves.  Certain 
points  of  interest  in  connection  with  their  structure  and  arrange- 
ment are  here  indicated  by  way  of  preparation  for  the  study. 

It  will  be  noted  that  the  spinal  nerves  are  mixed  nerves.  That 
is,  they  are  connected  with  both  ventral  and  dorsal  columns  of 
the  cord  and  contain  both  motor  and  sensory  fibers  until  they  have 


TERMINAL  BRANCHES    OF   NERVES  283 

made  several  divisions,  when  certain  of  the  sensory  fibers  are  no 
longer  found  in  the  same  sheath  with  the  others,  but  are  grouped 
into  nerves  which  belong  to  sensitive  surfaces. 

The  terminal  branches  of  all  nerve  fibers  differ  with  their  func- 
tion. The  fibrils  of  motor  spinal  nerves  end  as  tiny  expanded 
plates  (end  plates)  which  are  applied  to  muscle  fibers.  (See  Fig. 
178.)  Those  of  sensory  spinal  nerves  are  modified  for  the  purpose 
of  receiving  impressions  from  skin,  mucous  membranes,  joints, 
periosteum  and,  to  a  lesser  extent,  from  muscle  and  bone  tissues. 

Sensory 
nerve-fiber. 


Nerve-fiber 
bundle. 


FIG.    178. — MOTOR    NERVE-ENDINGS    OF    INTERCOSTAL    MUSCLE-FIBERS    OF    A 
RABBIT.     Xi5o.—(Siohr.) 

The  terms  origin  and  distribution  are  employed  in  the  description  of  indi- 
vidual nerves.  When  applied  to  motor  nerves  they  are  used  appropriately 
and  are  easily  understood,  but  in  connection  with  sensory  nerves  it  must  be 
remembered  that  their  origin  or  nerve  beginning  is  by  the  "terminal  branches. " 
The  impulse  transmitted  by  sensory  nerves  is  aroused  by  the  stimulus 
of  impressions  on  these  "branches"  and  received  by  the  central  cell;  while 
that  of  a  motor  nerve  originates  in  the  central  cell,  to  be  transmitted  to  a  muscle 
where  it  is  really  distributed. 

In  describing  mixed  nerves  it  is  necessary  to  conform  to  custom  and  speak 
of  the  whole  nerve  as  arising  by  its  central  connections  and  as  being  distributed 
at  the  periphery  (by  which  is  meant  the  place  where  its  function  is  manifested) . 

By  the  above  it  is  evident  that  the  conductivity  of  the  tissue  is 
specialized  in  the  axon  fibers;  the  sensibility  in  the  terminals  and 
cell  bodies.  The  chemical  changes  in  these  parts  are  supposed  to 
be  the  origin  of  nerve  impulse  or  nerve  force. 


CHAPTER  XX 


Cervical 


12  Thoracic 


5  Lumbar 


5  Sacral 

FIG.  179. — DIAGRAM  or 
SPINAL  NERVES. 


THE  SPINAL  NERVES 

There  are  thirty-one  pairs  of  spinal 
nerves.  They  leave  the  spinal  canal  at 
the  intervertebral  foramina  in  the  differ- 
ent regions  and  are  named  accordingly. 


Cervical. . 
Thoracic . . 
Lumbar.  . 

Sacral 

Coccygeal . 


8 

12 

5 
5 

i 


The  first  cervical,  emerging  above  the  atlas, 
is  called  the  suboccipital. 

The  cauda  equina. — The'spinal  cord,  being 
17  inches  long,  reaches  only  to  the  second 
lumbar  vertebra,  therefore  the  nerves  emerg- 
ing through  the  foramina  below  this  level  must 
have  lain  in  the  canal  for  some  distance  before 
leaving  it,  especially  those  which  appear  in 
the  lowest  or  pelvic  region.  If  the  canal  be 
opened  at  the  back  and  the  cord  lifted  out, 
these  long  nerves  are  seen  hanging  from  it  in 
a  crowd,  suggesting  the  appearance  of  a 
horse's  tail,  the  "cauda  equina,"  which  there- 
fore is  composed  of  the  lumbar,  sacral,  and  coc- 
cygeal  nerves  while  they  are  still  in  the  neural 
canal.  The  terminal  filament  extends  down- 
ward in  their  midst. 

All  spinal  nerves  divide  at  once  into 
posterior  and  anterior  divisions,  both  di- 
visions containing  motor  and  sensory 
fibers  (Fig.  181). 

The  posterior  divisions  send  nerves 
to  posterior  regions  of  neck  and  trunk; 
the  anterior  divisions  (communicate  with 
the  sympathetic  system,  and  then)  send 
nerves  to  anterior  and  lateral  regions  of 
284 


NERVE  PLEXUSES 


the  neck  and  trunk,  and  to  the  upper  and  lower  extremities.1 
In  all  regions  except  the  thoracic,  the  anterior  divisions  interlace 
with  each  other  to  form  plexuses  before  giving  off  nerves. 

A  nerve  plexus  is  a  network  formed  by 
branches  of  several  main  nerves  which  have 
different  central  connections.  (See  p.  296.) 
From  the  plexus  other  nerves  proceed  to 
their  separate  distributions. 

A  nerve  made  up  of  fibers  which  have 
been  part  of  a  plexus  conveys  impulses  to 
or  from  several  different  parts  of  the  spinal 
cord. 

The  most  important  plexuses  are: 

The  cervical  plexus  (formed  by  the  upper  four 
cervical  nerves). 

The  brachial  plexus  (formed  by  the  lower  four 
cervical  and  first  thoracic  nerves). 

The  lumbar  plexus  (formed  by  the  upper  three 
and  part  of  the  fourth  lumbar  nerves). 

The  sacral  plexus  (formed  by  the  lower  lum- 
bar, and  upper  three  and  most  of  fourth  sacral 
nerves). 

The  larger  nerves  only  are  described  in  the 
text.  Resumes  are  added  for  reference. 

For  nerves  supplying  the  joints  see  page  74. 


FIG.  1 80. — CAUDA  EQUINA. — 
(Morris.} 


FIG.  181. — SHOWING       DIVISION       OF 
NERVE. 

i,  Dura  mater;  2,  arachnoid;  3, 
ganglion  of  post,  root;  4,  ant.  root;  5, 
space  containing  spinal  fluid;  6,  post, 
division  of  nerve. — (H olden.) 


1  The  communicating  branches  to  sympathetic  ganglia  are  of  great  importance, 
serving  to  connect  the  cerebro-spinal  and  sympathetic  division  into  one  great  nerve 
system.  (They  are  the  white  rami  communicantes.) 


286 


ANATOMY   AND    PHYSIOLOGY 


CERVICAL  NERVES 


Posterior  divisions. — These  send  branches  to  the  back  of  the 
head  as  well  as  muscles  and  skin  of  the  neck.  Largest  posterior 
branch. — The  great  occipital  (from  second  cervical),  to  supply  the 
scalp. 

Anterior  divisions. — The  upper  four  form  the  cervical  plexus. 
The  lower  four  enter  the  brachial  plexus. 


FIG.  182. — THE  PHRENIC  NERVES,  RIGHT  AND  LEFT,  RUN  DOWNWARD  ON  EITHER 
SIDE  OF  THE  GREAT  VESSELS  AND  THE  HEART. — (After  Morris.) 

The  cervical  plexus. — Most  of  the  branches  of  this  plexus 
supply  muscles  of  the  neck  (front  and  side).  One  exception  is 
the  great  auricular  (auricularis  magnus)  which  supplies  the  external 
ear.  Another  is  the— 

Most  important  nerve  of  this  plexus,  the  phrenic. — It  passes 
downward  through  the  thorax  (between  the  lung  and  heart)  to 
supply  the  diaphragm  (Fig.  182).  Its  importance  is  due  to  the 
fact  that  the  diaphragm  is  one  of  the  principal  breathing  muscles, 


THE   BRACHIAL   PLEXUS  287 

and  the  nerve  has  for  that  reason  been  called  the  "internal  respira- 
tory nerve  of  Bell."  (Sir  Charles  Bell  was  a  famous  anatomist  in 
former  times.) 

The  brachial  plexus.- — This  plexus  is  so  named  because  most 
of  its  branches  supply  muscles  of  the  upper  extremity  (including 
the  shoulder)  and  those  connected  with  it. 

First  important  branch,  given  off  in  the  neck — the  long  thoracic. 
It  passes  downward  along  the  side  of  the  thorax  to  supply  the  an- 
terior serratus  muscle  (p.  102).  This  muscle  is  used  in  forced  res- 
piration and  -the  nerve  has  been  called  therefore  the  "external 
respiratory  nerve." 

The  greater  part  of  the  branchial  plexus  is  situated  in  the 
axilla;  most  of  its  branches  are  given  off  there 

f  supraspinatus 
Branches:  Suprascapular.  to      <  .   f 

{  mfraspmatus 

Three  large  cords:        Lateral,  medial,  posterior. 
Branches  of  the  cords: 

From  lateral  cord:        Thoracic,  to  pectoral  muscles. 

Musculo-cutaneous,  to  biceps  and  brachialis  (and 

their  integument). 
Upper  root  of  median  nerve. 
From  medial  cord :       Lower  root  of  median  nerve. 

Thoracic,  to  pectoral  muscles. 
Cutaneous,  to  integument  of  forearm. 
Ulnar,  to  ulnar  muscles. 

f  subscapularis,     teres     major, 
From  posterior  cord:    Subscapular  to     <  latissimus  dorsi  (the  long  sub- 

(  scapular}. 

Axillary,  to  deltoid  and  teres  minor. 
Radial,  to  posterior  of  forearm  and  hand. 

The  three  large  nerves  derived  from  the  brachial  plexus  are: 

The  ulnar  from  the  medial  cord. 

The  median  from  the  medial  and  lateral  cords. 

The  radial  from  the  posterior  cord. 

The  ulnar  nerve  runs  downward  in  the  medial  side  of  the  arm, 
passes  behind  the  medial  epicondyle  into  the  forearm,  and  ends 
in  the  palm  (Fig.  183). 

In  the  forearm  it  supplies:    Flexor  carpi  ulnaris. 

Flexor  digitorum  (profundus)  partially. 
In  the  hand  it  supplies:         Interossei. 

Little  finger  muscles. 

Thumb  muscles  (one  and  a  half). 


288 


ANATOMY  AND   PHYSIOLOGY 


Axillary  artery 


Suprascapular  nerve  and  artery 


Median  nerve 
Brachial  artery 


Lateral 
cord 


Pectoral 
muscle 


Ulnar  nerve  and 

artery 
Radial  nerve  and 

artery 


Branches  to  hand 


Deep  branch 

of  radial 

nerve 


Post,  interosse- 
ous  nerve 


FIG.  183. — BRACHIAL  PLEXUS  AND  AN- 
TERIOR NERVES. 


FIG.  184. — THE  RADIAL  NERVE. 


MEDIAN    AND    RADIAL    NERVES  289 

The  median  nerve  runs  downward  in  the  arm,  close  under  the 
border  of  the  biceps  muscle.  It  then  passes  in  front  of  the  elbow 
joint  into  the  forearm,  and  continues  between  the  layers  of  flexor 
muscles  to  the  palm. 

In  the  forearm  it  supplies:   Flexor  carpi  radialis. 

Flexor  digitorum  (sublimis). 

Flexor  digitorum  prof undus  (partially). 

Pronators. 
In  the  hand  it  supplies:  Thumb  muscles  (except  one  and  a  half). 

The  radial  nerve  passes  to  the  back  of  the  arm,  winding  across 
the  humerus  in  the  radial  groove,  under  the  triceps  muscle  (Fig. 

184). 

Just  above  the  elbow  it  divides  into  two  branches,  the  deep  and 
superficial  branches  of  the  radial  nerve. 

The  superficial  branch  is  a  cutaneous  nerve.  It  runs  downward 
in  the  radial  side  of  the  forearm  to  supply  integument  of  the  hand 
and  fingers,  posteriorly. 

The  deep  branch  passes  to  the  back  of  the  forearm,  lying  under 
cover  of  extensor  muscles,  all  of  which  it  supplies. 

Branches  of  the  radial  nerve: 

In  the  arm: To  the  triceps. 

To  brachio-radialis. 

To  brachialis  (partially). 
Branches  of  the  deep  branch  of  the  radial  nerve: 

In  the  forearm: To  the  extensor  carpi  radialis  (long  and 

short). 

To  the  extensor  digitorum  (communis). 

To  the  extensor  of  index  ringer. 

To  the  extensor  of  little  finger. 

To  the  extensors  of  the  thumb. 

To  the  Supinators. 

Resume.- — The  general  distribution  of  the  muscle  nerves  arising 
from  the  brachial  plexus,  is  to  deep  muscles  of  the  neck  and  the 
external  respiratory  muscle  (anterior  serratus);  to  shoulder  and 
axillary  muscles;  arm,  forearm  and  hand. 

The  three  long  muscular  nerves  derived  from  the  brachial  plexus 
are  the  ulnar  nerve  from  the  medial  cord,  running  down  behind 
the  medial  epicondyle  into  the  forearm  and  hand  (supplying  ulnar 
muscles,  little  finger  muscles  and  the  interossei,  and  a  part  of  the 
thumb  group) ;  the  median  nerve  from  the  medial  and  lateral  cords, 
19 


290 


ANATOMY   AND   PHYSIOLOGY 


running  down  along  the  medial  border  of  the  biceps  muscle  into  the 
forearm,  to  end  in  the  palm  (supplying  the  biceps  and  brachial 
muscle,  all  of  the  flexors  of  the  forearm  except  on  the  ulnar  side, 
and  most  of  the  thumb  muscles) ;  the  radial  nerve  from  the  pos- 
terior cord,  running  in  its  groove  to  the  front  of  the  lateral  epicon- 
dyle,  and  dividing  into  the  deep  and  superficial  branches  of  the  radial 
nerve.  By  the  radial  and  its  deep  branch  all  of  the  posterior  mus- 
cles of  the  arm  and  forearm  are  supplied. 

Nerves  of  the  skin  of  the  hand.^Front  of  the  thumb,  index, 
middle,  and  one-half  of  the  ring  finger,  the  median  nerve.  Back  of 
thumb,  index,  middle,  and  one-half  of  ring  finger,  the  superficial 


FIG.  185.— DORSAL  SURFACE  OF  LFFT 
HAND. — (Morris.) 


FIG.  1 86. — AN  INTERCOSTAL  NERVE. 
— (H  olden.) 


branch  of  the  radial  nerve.     Both  front  and  back  of  little  finger  and 
one-half  of  ring  finger,  the  ulnar  nerve. 

Points  of  interest. — The  ulnar  nerve,  in  the  arm,  is  with  the  inferior  pro- 
funda  artery  and  passes  behind  the  medial  epicondyle  (it  may  be  easily  felt  in 
the  groove  behind  the  epicondyle,  where  pressure  causes  a  sensation  of  pain 
and  tingling  as  far  as  the  little  finger).  In  the  forearm  it  is  on  the  ulnar  side 
of  the  ulnar  artery  and  they  pass  in  front  of  the  wrist. 

The  median  nerve,  in  the  arm,  is  with  the  biceps  muscle  and  brachial 
artery,  and  they  pass  in  front  of  the  elbow;  in  the  forearm,  it  lies  between  the 
deep  and  superficial  muscles  and  passes  with  their  tendons  in  front  of  the 
wrist. 

The  radial  nerve,  in  the  arm,  lies  in  the  groove  for  the  radial  nerve  be- 
tween two  heads  the  triceps  muscle,  with  the  superior  profunda  artery,  and 
comes  to  the  front  of  the  elbow. 

Its  superficial  branch,  in  the  forearm,  is  on  the  radial  side  of  the  radial 
artery;  it  winds  around  behind  the  wrist-joint. 


THORACIC    NERVES 


2-91 


The  deep  branch  of  the  radial  nerve  is  in  the  back  of  the  forearm  with  the 
dorsal  interosseous  artery;  they  do  not  extend  below  the  wrist. 

(For  the  distribution  of  nerves  to  the  principal  joints,  see  page  74.) 


THORACIC  NERVES  (FIG.  186) 

There  are  twelve  pairs  of  thoracic 
nerves : 

Posterior  divisions: — These  send 
branches  to  muscles  and  skin  of  the 
back. 

Anterior  divisions. — These  form 
the  intercostal  nerves;  the  first  assists 
in  the  formation  of  the  brachial 
plexus.  All  run  in  the  grooves  under 
the  borders  of  the  ribs,  supplying  in-  IJ 
tercostal  muscles,  also  the  skin  over 
the  muscles.  The  lower  ones  also 
supply  upper  abdominal  muscles  and 
skin.  They  accompany  intercostal 
arteries. 

LUMBAR  NERVES 

There  are  five  pairs  of  Lumbar 
Nerves. 

Posterior  divisions. — These  send 
branches  to  muscles  of  the  back;  and 
skin  of  the  back,  hip,  and  sacral  region. 


FIG.  187.— THE  FEMORAL 
NERVE. 


i,  Femoral  nerve;  2,  3,  small 
,  .   .   .  nerves  from  lumbar  plexus;  4,  5. 

Anterior  divisions.—  The  up  per  three  5,7,8,9,10,  n,  n,  branches  of 
and  a  portion  of  the  fourth  form  the  femoral  "erve;   I2>   «'.  *3>  M, 

long    saphenous    nerve   and   its 
lumbar  plexus.      The  remainder  of  the   branches;  15,  obturator  nerve;  16, 


23,  external    cutaneous  nerve.— 


fourth  and  the  whole  of  the  fifth  form 

the  lumbo-sacral  cord  (Fig.  187). 

The  lumbar  plexus.—  This  plexus 
lies  within  the  abdomen,  in  the  substance  of  the  psoas  muscle.  Its 
branches  supply  abdominal  walls,  and  front  and  sides  of  the  thigh 
(also  integument  of  both  regions).  They  are  all  given  off  in  the 
abdomen. 

Branches:  the  principal  are: 


ANATOMY   AND   PHYSIOLOGY 

Ilio-hypogastric,  cutaneous  to  hypogastrium,  and  over  the  ilium  (dorsum). 
Inguinal,  to  internal  oblique  and  transversus  muscles. 
Genito-femoral,  to  round  ligament  of  uterus,  cremaster  muscles  of  spermatic 
cord. 

Obturator,  to  the  external  obturator  and  the  four  adductors. 
Femoral,  to  the  quadriceps  muscle  (rectus  and  three  vasti). 

The  femoral  nerve  (anterior  crural}  is  the  largest  branch  of  the 
lumbar  plexus.  It  passes  under  the  inguinal  ligament,  from  the 
abdomen,  into  the  thigh  (on  the  lateral  side  of  the  femoral  artery), 
and  breaks  up  at  once  into  branches — cutaneous  and  muscular,  for 
the  four  large  divisions  of  the  quadriceps  extensor  muscle  and  the 
integument  which  covers  them. 

The  long  saphenous  branch  of  the  femoral  nerve  is  the  longest 
nerve  in  the  body,  running  nearly  the  whole  length  of  the  extrem- 
ity; it  supplies  integument  only,  on  the  medial  side  of  the  leg  and 
foot. 

The  lumbo-sacral  cord  passes  into  the  pelvis  to  unite  with 
sacral  nerves  and  to  form  the  sacral  plexus. 

SACRAL  NERVES 

Posterior  divisions. — These  send  branches  to  muscles  and  skin 
of  the  back  of  the  pelvis. 

Anterior  divisions. — The  upper  three,  and  greater  part  of  the 
fourth,  join  the  sacral  plexus. 

The  sacral  plexus.- — The  branches  of  this  plexus  supply  the 
muscles  within  and  around  the  pelvis,  the  posterior  part  of  the 
thigh,  and  the  entire  leg  and  sole  of  the  foot. 

Branches:  (All  leave  the  pelvis  through  the  great  sciatic  foramen.) 

Gluteal,  two  (superior  and  inferior}  to  glutei  muscles. 

Pudic,  to  the  levator  ani,  rectum  (sphincter  ani),  perineum,  and  external 
genital  organs.  (Reenters  the  pelvis  through  small  sciatic  foramen.) 

Small  sciatic,  to  posterior  thigh  and  external  genital  organs.  This  is  a 
cutaneous  nerve. 

Great  sciatic,  to  posterior  thigh,  and  entire  leg  and  foot  (except  medial 
border)  muscles  and  skin. 

The  great  sciatic  nerve  is  the  largest  nerve  in  the  body.  It 
leaves  the  pelvis  by  way  of  the  great  sciatic  notch  and  runs  down- 
ward between  posterior  thigh  muscles  to  the  popliteal  space, 
where  it  divides  into  tibial  and  common  peroneal  nerves  (Fig.  188). 


SCIATIC    NERVE 


2Q3 


The  only  portion  of  the  great  sciatic  nerve  which  is  not  covered  by  muscles, 
lies  in  the  deep  groove  between  the  great  trochanter  of  the  femur  and  the 
tuberosity  of  the  ischium. 


Branches: 

In  the  thigh.— To  the  Biceps, 
Semitendinosus. 
Semimembranosus. 
Calf  muscles. 

The  division  of  the  great  sciatic 
nerve  occurs  in  the  upper  part  of 
the  popliteal  space.  The  tibial 
nerve  (internal  popliteal)  runs 
down  through  the  popliteal  space 
(with  the  popliteal  artery  and 
vein)  to  the  leg.  It  then  descends 
under  cover  of  the  calf  muscles  to 
the  ankle;  below  the  medial  mal- 
leolus  it  divides  into  medial  and 
lateral  plantar  nerves. 

Branches: 

In  the  leg. — To  the  Tibialis  posticus. 
Flexor  digitorum  (longus). 
Flexor  hallucis. 

In  the  foot. — By  medial  plantar,  to 
great  toe  muscles  and  interossei. 

By  lateral  plantar,  to  muscles  of 
little  toe. 

The  tendons  of  the  tibialis  and  two 
long  flexors  of  toes  pass  behind  the 
medial  malleolus.  They  extend  the  foot. 

The  common  peroneal  nerve 
(external  popliteal)  winds  around 
the  neck  of  the  fibula  to  the  front 
of  the  leg,  and  divides  into  the 
deep  peroneal  and  superficial  pero- 
neal nerves. 

The  deep  peroneal  (formerly 
anterior  tibial)  descends  to  the 
ankle,  and  ends  on  thedorsum  of 
the  foot  between  the  first  and  second  toes. 


•Gluteal   n. 


Sciatic  n. 


'  Popliteal  artery 
•  Tibial  n. 

Peroneal  n. 


Ant.  tib.  artery 


Tibial  n. 

Post.  tib.  artery 


FIG.  188.— THE  SCIATIC  NERVE. 


294 


ANATOMY   AND    PHYSIOLOGY 


Branches: 

In  the  leg. — To  the  Tibialis  anticus. 
Extensor  hallucis. 
Extensor  digitorum  (longus). 
Peroneus  tertius. 

In  the  foot. — Extensor  digitorum  (brevis). 

The  tendons  of  these  muscles  pass  in  front  of  the  ankle-joint.     They  flex 
the  foot. 

The  superficial  peroneal  (musculo-cutaneous)  runs  downward 
in  the  substance  of  the  peroneal  muscles  to  the  foot. 

Branches: 

Muscular. — To  the  Peroneus  longus,  peroneus  brevis. 

Cutaneous. — To  dorsum  of  foot. 

Their  tendons  pass  behind  the  lateral  malleolus.     They  extend  the  foot. 


Tibialis  posterior 
Cruciate  ligament 


Tibialis 
posterior 

Tibialis 
anterior 


Tendo  Archillis 


Flexor  digitorum 

longus 
-^  Posterior  tibial 

artery 
Tibial  nerve 


Flexor  digitorum  longus 

FIG.  189. — RELATIONS  OP  PARTS  BEHIND  THE  MEDIAL  MALLEOLUS. — (Heath.} 

Points  of  interest. — The  superior  gluteal  nerve,  with  the  superior  gluteal 
artery;  the  sciatic  nerve,  with  the  sciatic  artery;  and  the  pudic  nerve,  with  the 
pudic  artery,  all  pass  out  from  the  pelvis  through  the  great  sciatic  for  amen;  the 
pudic  nerve  and  artery  return  through  the  small  sciatic  foramen. 

The  obturator  nerve  and  the  obturator  artery  pass  through  the  obturator 
foramen. 

The  femoral  nerve  passes  under  the  inguinal  ligament  on  the  lateral  side 
of  the  femoral  artery. 

THE  COCCYGEAL  PLEXUS 

The  remaining  sacral  nerves  and  the  coccygeal  nerve  communi- 
cate in  a  small  plexus,  which  is  important  in  that  it  sends  branches 
to  the  viscera  of  the  pelvis . 


NERVE   REFLEXES 


2Q5 


Summary 

The  spinal  nerves  are  distributed  to  all  skeletal  muscles  and 
integument  except  those  of  the  front  of  the  head,  face,  and  chin. 
Through  sympathetic  connections  they  also  supply  secreting  cells 
of  glands  and  walls  of  viscera. 

FUNCTIONS  OR  PHYSIOLOGY  OF  THE  SPINAL  CORD 
AND  SPINAL  NERVES 

The  spinal  cord  is  so  intimately  connected  with  the  brain  by 
conducting  fibers  in  the  tracts,  that  it  is  impossible  to  explain  all 
of  its  functions  without  referring  to  the  brain,  but  certain  ones 


{sp.c. 


FIG.  190. — DIAGRAM  SHOWING  THE  STRUCTURES  INVOLVED  IN  THE  PRODUCTION  OF 

REFLEX  ACTIONS. — (G.  Bachman.) 

r.s.,  Receptive  surface;  af.n.,  afferent  nerve;  e.c.t  emissive  or  motor  cells  in  the 
anterior  horn  of  the  gray  matter  of  the  spinal  cord,  sp.c;  ef.n.,  efferent  nerves  dis- 
tributed to  responsive  organs,  e.g.,  directly  to  skeletal  muscles,  sk.rn.,  and  indi- 
rectly through  the  intermediation  of  sympathetic  ganglia,  sym.  g.,  to  blood-vessels, 
&.fl.,'and  to^glands,  g.  The  nerves  distributed  to  viscera  are  not  represented. 

may  be  exercised  independently,  and  a  few  of  these  will  be  con- 
sidered briefly  in  this  connection. 

The  spinal  cord  a  center  for  reflex  action.  This  is  one  of  the 
most  important  of  its  functions  and  the  simplest  form  of  nerve 
and  muscle  action.  Acts  which  may  be  performed  without 
thinking  of  them  are  reflex,  also  those  which  are  performed 
independently  of  the  will  although  with  perfect  consciousness. 


296  ANATOMY    AND    PHYSIOLOGY 

For  example,  we  shiver  with  cold,  or  tremble  from  excitement; 
these  are  purely  reflex  acts  of  which  we  may  be  conscious  although 
we  are  unable  to  control  them;  the  action  of  the  heart  is  some- 
times very  evident  to  the  senses,  as  in  palpitation,  etc.,  but  beyond 
our  power  to  regulate. 

In  each  lateral  half  of  the  cord  the  cell  tissue  is  grouped  in 
crescents.  Fibers  in  the  posterior  tracts  transmit  sensory  impulses 
from  various  parts  of  the  body  to  cells  in  the  posterior  horns  of  the 
crescents.  Fibers  in  the  anterior  tracts  transmit  motor  impulses 
from  cells  in  the  anterior  horns  to  various  parts  of  the  body  (their 
axons  arise  in  cells  of  the  anterior  horns)  (Fig.  190). 

Here  we  have  the  simple  reflex  arc,  or  the  apparatus  for 
reflex  muscle  action. — A  sensory  or  afferent  nerve  receives  an 
impression,  and  transmits  a  series  of  impulses  to  the  spinal  cord. 
These  are  received  by  a  cell  which  in  its  turn  is  stimulated,  and 
liberates  energy  to  be  conducted  by  a  motor  or  efferent  nerve  to  a 
muscle,  and  the  muscle  contracts;  or  to  a  gland— the  gland 
secretes;  or  to  a  vessel  wall — the  caliber  is  changed.  These  acts 
are  comparatively  simple. 

Most  muscle  activities,  however,  are  complex,  requiring  the 
combined  action  of  several  organs;  in  these  cases  many  motor  cells 
and  nerves  must  be  stimulated,  and  this  is  accomplished  by  means 
of  additional  neurons  within  the  cord,  whose  fibers  associate  the 
activities  of  different  regions.  For  instance,  an  unsuspected  blow 
upon  the  hand  is  followed  instantly  by  a  drawing  back  of  the  hand 
and  arm — most  of  the  muscles  of  the  upper  extremity  will  have 
been  called  into  action;  in  other  words,  many  motor  cells  (in  the 
lower  cervical  region  of  the  cord)  have  been  stimulated  to  a  sudden 
liberation  of  energy,  showing  the  effect  of  one  stimulus  when 
conducted  by  connecting  fibers  to  many  cells  in  the  cord. 

Walking  was  in  the  beginning  a  purely  voluntary  act,  but  the 
centers  which  control  it  become,  by  education,  independent,. and 
it  takes  its  place  among  the  reflexes.  So  with  piano-playing,  and 
many  other  acts. 

The  complicated  motor  response  is  provided  for  by  the  arrangement  known 
as  a  nerve  plexus,  which  is  formed  by  interlacing  branches  of  nerve  trunks. 
An  illustration  is  seen  in  the  brachial  plexus,  where  five  large  trunks  are 
reduced  to  three  while  passing  under  the  shoulder  joint;  then,  by  branching 
and  interlacing,  the  fibers  are  so  arranged  that  each  nerve  contains  fibers 


TENDON    REFLEXES  297 

from  two  or  three  of  the  main  trunks  proceeding  from  the  plexus  and  is  dis- 
tributed to  a  group  of  muscles  acting  in  harmony. 

Tendon  reflex. — A  familiar  example  of  tendon  reflex  is  the 
"knee  jerk"  or  patellar  reflex.  This  may  be  elicited  by  striking 
the  patellar  tendon  when  partly  stretched.  The  impression  thus 
produced  quickly  reaches  the  motor  cells  which  innervate  the 
quadriceps  muscle,  and  the  leg  is  slightly  and  suddenly  extended. 
(There  are  several  tendon  reflexes.) 

Skin  reflex. — Irritation  of  the  sole  of  the  foot  causes  the 
plantar  muscles  to  contract,  a  plantar  reflex.  Scratching  the  skin 
of  the  side  of  the  abdomen  causes  contraction  of  abdominal 
muscles,  abdominal  reflex.  (There  are  other  skin  reflexes.) 

The  spinal  cord  contains  centers  for  controlling  the  tone  of 
vessel  walls  or  vascular  tone.  Also  for  stimulating  the  action  of 
secreting  glands,  and  for  muscle  action  of  viscera.  These  functions 
are  exercised  through  the  sympathetic  ganglia  with  which  it  is 
widely  connected;  they  will  be  referred  to  in  Chapter  XXII. 

Finally,  it  contains  centers  which  influence  (or  control)  certain 
processes  of  nutrition — trophic  centers. 

It  appears  at  once  that  the  spinal  cord  is  able,  from  the  wide 
distribution  of  its  nerves,  to  provide  for  most  of  the  activities  of 
the  body. 

Taken  as  a  whole  it  may  be  regarded  as  a  great  common  center 
of  sensation  and  motion;  and  because  of  many  connecting  fibers 
running  upward,  downward,  and  transversely,  it  can  combine 
and  to  some  extent  regulate  the  functions  of  many  different  parts, 
so  that  systematic  groups  of  movement,  or  series  of  movements,  may 
be  executed  by  organs  more  or  less  distant  in  the  body. 

In  other  words,  the  spinal  cord  can  to  some  extent  coordinate 
the  functions  of  the  spinal  nerves  and  skeletal  muscles. 

To  repeat  the  functions  of  the  spinal  cord,  they  are  to  preside 
over: 

1.  Reflex  action. 

2.  Muscle  tone. 

3.  Vessel  tone. 

4.  The  action  of  secreting  glands. 

5.  Nutrition  (trophic  action). 

6.  Coordination  of  skeletal  muscles. 


2p8  ANATOMY  AND   PHYSIOLOGY 

These  may  all  be  exercised  independently  of  the  brain,  by  cells 
in  the  posterior  and  anterior  horns  with  their  sensor  and  motor 
nerve  connections.  (Other  functions  will  be  mentioned  in  connec- 
tion with  those  of  the  brain.) 

The  function  of  the  spinal  nerves  is  to  connect  all  parts  of  the 
body  (except  face,  chin  and  anterior  part  of  head)  with  the  spinal 
cord,  for  the  purpose  of  conducting  sensor  and  motor  impulses  to 
and  from  the  cord. 

NERVE  STIMULUS 

In  referring  to  motor  nerves  we  have  thus  far  mentioned  their 
natural  stimulus  only,  that  is — the  impulse  generated  by  a  sensor 
or  motor  cell.  The  electric  current  applied  to  a  motor  nerve  in  any 
part  of  its  course  will  excite  its  activity,  showing  in  muscle  contrac- 
tion, etc.  This  is  an  artificial  stimulus,  and  the  most  powerful 
one  known. 


CHAPTER  XXI 
THE  BRAIN  AND  CRANIAL  NERVES 

The  cerebro-spinal  or  central  nerve  system  comprises  the 
Brain  and  Spinal  Cord  with  their  nerves.  The  spinal  cord  and 
its  nerves  are  already  described  in  Chapters  XIX  and  XX. 

The  brain1  is  ovoid  in  shape,  composed  of  gray  cells  and  white 
fibers,  situated  within  the  cranial  cavity  and  continuous  through 
the  foramen  magnum  with  the  spinal  cord. 


FIG.  191. — THE  EXTERNAL  SURFACE  OF  THE  BRAIN. — (Deaver.) 

The  surface  consists  of  gray  cells  and  their  branches  and  is 
called  the  cortex  of  the  brain,  while  the  interior  is  white,  with  several 
ganglia  imbedded  within  it. 

The  surface  or  cortex  of  a  well-developed  brain  is  marked  by 
many  fissures,  separating  curved  ridges  called  convolutions  (or 
gyres),  the  number  and  depth  of  which  correspond  with  the  degree 
of  development,  the  brain  of  a  new-born  child  being  comparatively 
smooth. 

1  A  review  of  pages  277  and  278  is  recommended  before  studying  the  description 
of  the  brain. 

299 


3oo 


ANATOMY   AND    PHYSIOLOGY 


The  white  portion  is  composed  of  white  fibers.  They  run  in 
many  directions.  Some  connect  the  different  main  divisions  of 
the  brain;  others  run  from  one  part  of  the  cortex  to  another; 
others  still,  in  great  number,  connect  the  brain  and  spinal  cord 
(Fig.  192).  Taken  together,  they  make  up  the  mass  of  the  brain 
itself. 

The  brain  has  four  principal  parts,  the  cerebrum,  cerebellum, 
medulla  oblongata,  and  pons  Varolii. 


FIG.  192. 

The  letters  mark  white  fibers.  They  connect  the  cortex  with  other  parts,  also 
different  parts  of  cortex  together.  Many  fibers  are  seen  to  pass  through  the  basal 
ganglia.  The  Roman  numerals  indicate  nerves. — (Brubaker,  after  Starr.} 

The  cerebrum  is  the  largest  division  and  occupies  nearly  the 
whole  cranial  vault.  It  is  divided  into  two  hemispheres,  right  and 
left,  by  a  longitudinal  fissure.  At  the  bottom  of  this  fissure  white 
fibers  are  seen  to  pass  from  one  side  to  the  other,  thus  forming  a 
transverse  commissure,  connecting  the  hemispheres,  and  called  the 
corpus  callosum  (Fig.  193).  Each  hemisphere  is  marked  off  by 
specially  deep  fissures,  into  lobes,  the  principal  ones  being  the 
frontal,  parietal,  occipital,  and  temporal.  The  principal  fissures 
between  the  lobes  are:  the  fissure  of  Rolando  between  the  frontal 
and  parietal;  the  parieto-occipital,  between  the  parietal  and  occi- 


THE   BASAL    GANGLIA 


3OI 


pital;  and  the  fissure  of  Sylvius,  between  the  temporal  lobe  below 
and  the  frontal  and  parietal  above  it. 

Important  note. — The  fissure  of  Rolando  is  often  called  the  central  fissure, 
and  the  convolutions  in  front  of  and  behind  it,  are  called  the  central  convolutions 
(anterior  and  posterior  central). 

Within  the  white  substance  of  the  hemispheres  are  the  largest 
ganglia  in  the  brain,  and  since  they  are  situated  near  the  base, 
they  are  called  basal  ganglia.  They  are  the  optic  thalamus,  the 
lentiform  nucleus,  and  the  caudate  nucleus  (Fig.  195).  The  white 


FIG.  193. — MEDIAN  SURFACE  OF  A  HEMISPHERE,  SHOWING  THIRD  AND  FOURTH 
VENTRICLES;  ALSO  THE  CORPUS  CALLOSUM  DIVIDED,  AND  THE  STRUCTURE  OF  THE 
CEREBELLUM  WITH  THE  PONS  IN  FRONT  OF  IT.  THE  PITUITARY  BODY  is  SUSPENDED 
FROM  THE  FLOOR  OF  THE  THIRD  VENTRICLE. — (Deaver.) 

matter  between  the  optic  thalamus  and  the  other  two,  constitutes 
the  internal  capsule.  Here  are  the  fibers  which  connect  centers  in 
the  cortex  with  those  in  the  spinal  cord;  hence  the  great  importance 
of  the  internal  capsule. 

The  white  fibers  of  the  cerebrum  are  classified  in  three  groups:  i.  those 
which  connect  different  parts  in  the  same  hemisphere,  or  association  fibers; 
(Fig.  201)  2.  those  which  connect  parts  in  one  hemisphere  with  similar 
parts  in  the  other,  or  commissural  fibers;  3,  those  which  connect  the 
cortex  with  the  ganglia  of  the  brain  and  spinal  cord,  or  projection  fibers 
(Fig.  192  shows  projection  fibers  of  the  right  half  of  the  brain). 

The  hemispheres  are  not  solid,  but  each  encloses  a  cavity 
called  the  lateral  ventricle,  shaped  like  the  italic  letter  /  with  a 


302 


ANATOMY   AND   PHYSIOLOGY 


projecting  arm  (laterally  and  downward).  The  extremities  of  the 
ventricle  are  called  horns;  the  anterior  horn  being  in  the  frontal 
lobe,  the  posterior  horn  in  the  occipital,  and  the  lateral  or  descend- 
ing horn  in  the  temporal  lobe.  The  great  ganglia  of  the  brain  are 
in  the  floor  of  the  lateral  ventricles  (hence  called  basal  ganglia). 

The  lateral  ventricles  are  named 
like  the  hemispheres — right  and  left. 

(There  are  certain  other  basal  ganglia 
which  are  important,  although  smaller  in 

size.) 

The  cerebellum,  or  little  brain, 
also  consists  of  white  matter  covered 
.6  with  gray.  It  has  two  hemispheres 
which  are  not  definitely  separated 
like  the  hemispheres  of  the  cerebrum, 
but  are  connected  by  a  median  por- 
tion called  the  vermis,  or  worm.  The 
convolutions  are  but  slightly  curved 
and  are  called  ridges,  and  the  furrows 
(or  sulci)  are  very  deep;  a  section 
shows  that  they  are  so  arranged  as 
to  resemble  the  branches  of  the  tree 
called  arbor  mta,  (Fig.  193). 

The  cerebellum  is  situated  in  the 


FIG.  194. — PONS  AND   MEDULLA, 
ANTERIOR   SURFACE. 


i,  2,  3,  Structures  belonging  to 
cerebrum;  4,  crura  of  cerebrum;  5, 


pons  varolii;  9,  10,  n    13,  14     cerebellar  fossae  of  the  occipital  bone. 

lateral  surface  and  membranes  of 

medulla;  7,  pyramid;  8,  decussa-  The  medulla  oblongata,  although 

median'    ES^USr,  *%$*    SitUated  ™Mn  ^  Cram'Um  ^  fr°nt 
nerves;  28,  29,  ist  and  2 d  spinal    of  the  foramen  magnum),  is  the  up- 

nerves.— (Sappey.)  "  ,  ^ 

per  enlarged  portion  of  the  spinal 
cord  and,  like  it,  is  white  externally  and  gray  within. 

Its  anterior  columns  are  called  the  pyramids  or  pyramidal 
tracts,  and  consist  of  motor  fibers  passing  downward  from  the 
brain.  Most  of  the  fibers  of  each  pyramid  cross  to  the  opposite 
side,  appearing  to  interlace  in  the  median  fissure,  the  decussation 
of  the  pyramids,  to  form  the  crossed  pyramidal  tract;  the  others 
pass  downward  as  the  direct  pyramidal  tract  and  cross,  a  few 
at  a  time,  at  lower  levels  in  the  cord.  Thus  it  is  that  motor 
fibers  coming  from  one  side  of  the  brain  pass  to  the  other  side 


VENTRICLES    OF   BRAIN  303 

of  the  cord,  and  this  is  the  explanation  of  paralysis  of  one  side 
of  the  body,  following  injuries  of  the  other  side  of  the  brain. 

The  posterior  columns  of  the  medulla  contain  sensory  fibers 
going  upward  to  the  brain,  while  the  lateral  tracts  contain  both 
motor  and  sensory  fibers  (like  the  cord).  Most  of  the  sensory 
fibers  also  cross  at  different  levels. 

The  medulla  contains  centers  for  the  most  important  nerves  of 
the  body — respiratory,  cardiac,  vaso-motor,  etc. 

The  pons  Varolii,  or  bridge  of  Varolius,  is  situated  in  front  of 
the  medulla,  below  the  cerebrum  and  cerebellum,  and  so  named 
because  fibers  run  through  it  from  all  three  of  the  other  parts  of 
the  brain,  as  though  it  were  a  bridge  between  them.  It,  also,  is 
white  externally  and  gray  within,  and  is  not  unlike  the  cord, 
although  in  a  still  more  modified  form  than  the  medulla. 

Two  large  nerve  bundles  are  seen  diverging  from  the  anterior  border  of  the 
pons,  the  crura  of  the  cerebrum  (often  called  peduncles).  They  contain  all  of 
the  motor  and  sensory  fibers  of  the  cerebrum  which  pass  between  the  pons 
and  the  cord.  The  fibers  to  and  from  the  cerebellum  form  peduncles  of 
the  cerebellum  (smaller  in  size). 

THE  FIVE  VENTRICLES  OF  THE  BRAIN  (Fig.  195) 

The  five  ventricles  are  different  portions  of  one  cavity,  which  is 
continuous  with  the  central  canal  of  the  spinal  cord.  The  two 
lateral  ventricles  have  been  mentioned.  The  third  ventricle  is 
between  them,  and  the  fourth  ventricle  is  behind  the  third,  being 
in  the  medulla  and  pons;  some  of  the  most  important  nuclei  or 
centers  of  the  body  are  imbedded  in  the  floor  of  the  fourth  ventricle. 

Each  lateral  ventricle  communicates  with  the  third  through  an 
opening  called  the  foramen  of  Munro;  the  third  communicates  with 
the  fourth  through  the  aqueduct  of  the  cerebrum  (aqueduct  of 
Sylvius),  a  slender  canal  in  the  crura  and  pons;  and  the  fourth 
ends  in  the  central  canal  of  the  cord.  These  spaces  are  therefore 
continuous,  and  they  contain  cerebro-spinal  fluid. 

The  so-called  fifth  ventricle  is  not  a  portion  of  the  general  cavity — not  a 
true  ventricle.  It  is  a  narrow  space  in  front  of  the  third,  having  no  opening 
whatever. 

Clinical  notes. — Hydrocephalus  is  caused  by  an  accumulation  of  fluid  in 
the  ventricles,  enlarging  them  and  pressing  upon  the  brain  substance,  and 


304  ANATOMY   AND   PHYSIOLOGY 

subsequently  upon  the  bones  of  the  skull.  It  is  very  likely  to  occur  in 
children  who  have  rachitis,  or  " rickets." 

By  a  foramen  in  the  arachnoid  membrane,  the  ventricular  cavities  and 
central  canal  communicate  with  the  subarachnoid  space,  allowing  cerebro- 
spinal  fluid  to  flow  through  all  of  these  parts.  (See  p.  281),  Arachnoid. 

Surgical  note. — Because  of  this,  the  operation  of  lumffar  puncture  may 
relieve  the  pressure  of  hydrocephalus. 

A  similarity  in  structure  and  arrangement  of  parts  is  plainly  evident  in 
the  brain  and  spinal  cord.  Recall  the  cord — a  collection  of  nerve  fibers, 


FIG.  195.  —  THE  VENTRICLES,  SHOWING  BASAL  GANGLIA  IN  THE  FLOOR  OF  THE 
LATERAL  VENTRICLES.  —  (Hirschfeld  and 


a,  Anterior  portion  of  corpus  callosum;  ft,  caudate  nucleus;  c,  location  of  lentiform 
nucleus;  d,  optic  thalamus;  h,  i,  quadrigeminal  bodies;  g,  third  ventricle;  o,  fourth 
ventricle;  p,  medulla.  The  fifth  ventricle  is  in  front  of  e. 

the  greater  number  running  up  or  down,  but  with  many  passing  from  one 
side  to  the  other;  a  central  canal  surrounded  by  collections  of  "gray  matter"; 
two  lateral  halves  connected  by  transverse  commissural  fibers. 

These  parts  may  all  be  traced  in  the  brain.  The  central  canal  extends 
through  the  medulla  and  pons  into  the  cerebrum,  expanding  into  a  general 
ventricular  cavity.  Gray  matter  (ganglia)  lies  close  to  this  canal,  even  pro- 
jecting into  it.  The  white  fibers  are  here,  but  they  diverge  on  every  side,  and 
many  take  new  directions;  also  the  halves  of  the  brain  are  connected  by 
transverse  (commissural)  fibers  (the  corpus  callosum).  The  brain  has  one 


THE   DURA   MATER  305 

part  not  found  in  the  cord  (and  a  most  important  part),  viz.,  a  covering  of 
"gray  matter,"  or  cortex. 


THE  MEMBRANES  OF  THE  BRAIN 

These  are  three  in  number,  the  pia  mater,  arachnoid,  and  dura 
mater,  like  those  of  the  cord,  and  continuous  with  them. 

The  pia  mater  fits  closely  to  the  brain,  following  all  convolu- 
tions and  uneven  surfaces;  it  is  necessary  to  the  life  of  the  brain,  as 
periosteum  is  to  bone,  and  for  the  same  reason — it  bears  the  blood- 
vessels which  nourish  it. 

The  arachnoid  lies  close  to  the  pia  but  stretches  across  the 
furrows,  leaving  subarachnoid  spaces  for  cerebro-spinal  fluid  as  in 
the  spinal  cord.  The  largest  spaces  are  at  the  base  of  the  brain 
where  the  greatest  irregularities  of  surface  are  found. 

The  dura,  firm,  white  and  tough,  covers  the  others  loosely  and 
lines  the  entire  skull,  taking  the  place  of  periosteum.  It  has  a 
number  of  meningeal  arteries  branching  in  its  substance,  for  its 
own  nourishment  and  the  nourishment  of  the  skull  bones  (since  it 
is  their  internal  periosteum).  It  sends  layers  between  the  large 
divisions  of  the  brain — one  between  the  hemispheres  of  the  cere- 
brum is  called  the  falx  cerebri,  and  one  stretched  over  the  cere- 
bellum is  called  the  tentorium  cerebelli.  They  support  the  weight 
of  portions  of  the  brain  in  different  positions  of  the  head. 

The  dura  also  presents  several  large  veins  called  sinuses  which 
collect  the  blood  from  the  brain.  The  largest  are  the  sagittal 
(longitudinal)  running  from  front  to  back  in  the  median  line,  and 
the  two  transverse  sinuses  (lateral)  right  and  left  which  end  in  the 
internal  jugular  vein  at  the  jugular  foramen. 

Surgical  note. — The  transverse  or  lateral  sinus  lies  partly  in  a  deep 
groove  on  the  mastoid  bone  (sigmoid  groove)  and  this  adds  to  the  gravity  of 
operations  in  the  mastoid  region. 

Clinical  note. — Inflammation  of  the  membranes  is  meningitis.  When 
affecting  the  dura  it  is  p  achy  meningitis;  when  it  is  of  the  pia  and  arachnoid, 
it  is  leptomeningitis. 

THE  CRANIAL  NERVES 

There  are  12  pairs  of  cranial  nerves.  They  are  seen  at  the 
base  of  the  brain  and  leave  the  skull  through  various  foramina  in 


306 


ANATOMY  AND  PHYSIOLOGY 


the  cranial  bones.     Some  are  nerves  of  motion,  some  of  sensation 
and  some  are  mixed  (Fig.  196).     They  are  named  as  follows: 

1.  Olfactory.  7.  Facial. 

2.  Optic.  8.  Acoustic  or  auditory. 

3.  Oculo-motor.  9.  Glosso-pharyngeal. 

4.  Trochlear,  or  pulley  nerve.  10.  Vagus,  or  pneumo  gas  trie. 

5.  Trifacial,  or  trigeminus.      u.  Spinal  accessory. 

6.  Abducens.  12.  Hypoglossal. 


First,  olfactory 


Third,  oculo-motor 
Fourth,  pathetic 

(trochlear) 
Fifth,  trifacial 
Sixth,  abducens 
Seventh,  facial 
Eighth,  auditory 

Ninth,  glosso-pharynxal 

Tenth,  vagus 

Eleventh,  spinal  accessory 


Twelfth,  hypoglossal 


FIG.  196. — BASE  OF  BRAIN  AND  CRANIAL  NERVES,  SHOWING  RELATION  OF  THE  PONS 
MEDULLA,  AND  CEREBRUM. — (Monat  and  Doyen;  Brubaker.) 

The  first,  or  olfactory  (Fig.  196),  is  the  nerve  of  smell.  Being 
sensory  it  is  traced  toward  the  brain. 

Minute  nerves  from  the  upper  part  of  the  nasal  mucous  membrane 
(olfactory  region),  pass  up  through  the  sieve-like  plate  of  the  ethmoid  bone  and 
enter  the  olfactory  bulb;  from  the  bulb,  a  soft  band  of  fibers  called  the  olfactory 
tract  proceeds  to  the  brain;  most  of  them  finally  reach  the  temporal  lobe, 
where  they  end  in  the  center  for  the  sense  of  smell,  or  olfactory  center. 


The  second,  or  optic  (Fig.  197),  is  the  nerve  of  vision, 
begins  in  the  retina. 


It 


The  retinal  fibers  are  gathered  to  form  the  nerve,  which  passes  through  the 
optic  foramen  into  the  cranial  cavity.  The  two  optic  nerves  meet  above  the 
body  of  the  sphenoid  bone  and  most  of  the  fibers  cross  each  other  there, 


THE   TRIFACIAL  NERVE  307 

forming  the  optic  commissure  (or  chiasm),  and  then  proceed  to  certain  ganglia, 
from  which  the  visual  impressions  are  conveyed  to  the  visual  centers  of 
the  occipital  lobes.  (Fig.  194,  16,  optic  chiasm.) 

The  third,  or  oculo-motor  (Fig.  197),  is  the  mover  of  the  eyes. 
It  proceeds  from  the  base  of  the  brain  and  enters  the  orbit,  to  sup- 
ply four  of  the  muscles  of  the  eyeball,  and  also  the  elevator  of  the 
upper  lid.  (Eye  muscles  thus  supplied:  Superior,  inferior,  and 
internal  recti,  and  inferior  oblique.  See  p.  343,  orbital  muscles.) 

By  the  action  of  the  first  three  the  eye  is  turned  upward,  downward  and 
inward;  the  inferior  oblique  turns  it  upward  and  outward. 


a  7       10  v 

FIG.  197. — NERVES  OF  THE  ORBIT. 

i,  Optic  nerve;  2,  Oculo-motor  (3d) ;  5,  abducens  (6th).     Other  figures  mark  various 
branches.     10,  Ciliary  ganglion. — (Sappey.) 

The  third  nerve  supplies  also  the  circular  fibers  of  the  iris  which 
contract  the  pupil  of  the  eye,  and  the  accommodation  muscle — by 
which  the  eye  is  focussed  for  viewing  objects  at  different  distances. 

The  fourth,  or  trochlear  nerve,  is  so  called  because  the  tendon 
passes  through  a  loop  of  fascia  and  bends  around  like  a  rope  on 
a  pulley  or  trochlea.  It  supplies  the  muscle  which  rolls  the  eye 
downward  and  outward  (the  superior  oblique  muscle). 

The  fifth,  or  trifacial  (trigeminal),  is  the  great  sensory  nerve 
of  the  face,  nose  and  throat.  Some  motor  fibers  for  muscles  of 
mastication  accompany  the  sensory  fibers  and  the  nerve  is 
described  as  having  two  roots;  sensory  and  motor. 

The  sensory  root  has  a  large  ganglion,  semilunar  (or  Gasserian)  ganglion, 
and  in  front  of  this  it  is  in  three  divisions,  called  the  ophthalmic,  maxillary, 
and  mandibular  nerves.  The  ophthalmic  nerve  lies  in  the  orbit ;  it  is  the  nerve 
of  sensation  of  the  structures  contained  therein;  also  of  the  eyelids  and  side 
of  the  nose.  The  maxillary  nerve  appears  at  the  infraorbital  foramen.  It 
is  the  nerve  of  sensation  for  the  upper  teeth  and  the  cheek  and  temple.  The 


308  ANATOMY  AND   PHYSIOLOGY 

mandibular  nerve  is  in  the  infratemporal  fossa,  and  is  the  nerve  of  sensation 
for  the  lower  teeth  and  structures  of  the  lower  jaw.  The  motor  root  joins  this 
branch  to  supply  the  muscles  of  mastication. 

The  nerve  of  the  sense  of  taste,  called  the  lingual  (or  gustatory},  accom- 
panies the  mandibular  nerve,  from  the  anterior  two-thirds  of  the  tongue. 

Surgical  notes.— Facial  neuralgia  is  sometimes  so  severe  and  intractable 
that  the  semilunar  ganglion  is  removed  by  the  surgeon.  This  interferes  with 
sensation  of  the  face,  but  not  with  motion. 

Three  sensitive  points  on  the  face  where  three  sensory  branches  of  the 
trifacial  pass  through  foramina  are:  the  supraorbital  foramen,  for  the  supra- 


FIG.  198. — THE    DISTRIBUTION  OF  THE  THREE  DIVISIONS  OF  THE  FIFTH  NERVE. — 

(Leidy.) 

orbital  branch  of  the  ophthalmic;  the  infraorbital  foramen  for  the  infra- 
orbital  branch  of  the  maxillary;  the  mental  foramen  for  the  mental  branch 
of  the  mandibular.  Section  of  these  nerves  is  sometimes  done  for  facial 
neuralgia. 

The  sixth,  or  abducens,  is  a  motor  nerve,  supplying  the 
external  rectus  muscle,  which  turns  the  eye  outward,  or  abducts 
it. 

The  seventh,  or  facial  (Fig.  199),  is  a  motor  nerve.  It  passes 
through  the  channel  in  the  petrous  bone  called  the  facial  or 
Fallopian  canal  (which  brings  it  close  to  the  middle  ear).  Emerg- 
ing from  the  skull  it  passes  forward  through  the  parotid  gland, 
and  divides  into  many  branches  supplying  all  the  muscles  of 
expression. 


ACOUSTIC   NERVE 


309 


Clinical  note. — If  this  nerve  is  paralyzed,  the  side  of  the  face  supplied  by 
the  injured  nerve  droops  and  is  useless,  and  the  eye  fails  to  close.  The  face 
will  be  drawn  toward  the  «w-injured  side  by  muscles  supplied  by  the  opposite 
nerve;  this  is  plainly  seen  if  the  patient  smiles,  or  attempts  to  whistle. 

The  eighth,  or  auditory  (acoustic),  is  a  sensory  nerve.  It  has 
two  portions — the  cochlear,  or  proper  nerve  of  hearing,  and  the 
vestibular,  or  nerve  of  equilibration.  Both  pass  from  the  internal 
ear  through  the  internal  auditory  canal  to  the  medulla.  (See  p. 
333,  Nerves  of  the  Internal  Ear.) 


FIG.  199. 
The  figures  mark  the  branches  of  the  seventh  or  facial  nerve. — (Holdcn.) 

The  ninth,  or  glosso-pharyngeal,  is  a  mixed  nerve.  The  motor 
fibers  pass  from  the  medulla  through  the  jugular  foramen  and 
supply  the  muscles  of  the  tongue  and  pharynx,  as  its  name  suggests. 
The  sensory  fibers  convey  sensations  of  taste  from  the  tip  and  back 
part  of  the  tongue.  Bitter  things  are  especially  appreciated  by  the 
glosso-pharyngeal. 

The  tenth,  or  vagus  (pneumogastric),  is  a  mixed  nerve.  It  is 
traced  from  the  medulla  through  the  jugular  foramen. 

Branches. — Laryngeal  to  larynx;  pharyngeal  to  pharynx;  car- 
diac to  the  heart;  pulmonary  to  the  lungs;  and  others,  indirectly, 
to  the  stomach,  liver,  spleen,  and  intestines. 

It  regulates  the  action  of  the  heart  and  the  act  of  swallowing; 


3io 


ANATOMY   AND    PHYSIOLOGY 


it  is  the  sensory  nerve  of  the  air  passages  from  the  larynx  down, 
and  of  the  alimentary  tract  from  the  pharynx  down. 

The  eleventh,  or  spinal  accessory,  is  traced  from  the  medulla 
through  the  jugular  foramen,  with  the  ninth  and  tenth.  It 
supplies  the  sterno-mastoid  and  trapezius  muscles  with  motor 
nerves.  (A  portion  of  it  is  accessory  to  the  vagus.) 

The  twelfth,  or  hypo-glossal  (under  the  tongue),  supplies  the 
muscles  of  the  tongue  and  those  connecting  it  with  the  jaw  and 
hyoid  bone;  also  the  ribbon  muscles  in  front  of  the  neck. 

Summary 

The  nerves  of  the  cerebro-spinal  system  are  distributed  to 
all  voluntary  muscles,  and  to  all  sensitive  structures,  as  skin,  mucous 
membranes,  lining  of  joints,  and  periosteum.  They  are  the  nerves 
of  conscious  life. 

CRANIAL  NERVE  SUPPLY  TO  CERTAIN  MUSCLE  GROUPS 


Region. 

Muscles. 

Name. 

Head 

Of  scalp  and  face 

Facial  or  7th 

Of  tongue 

Hypo-glossal  or  i2th 

Of  mastication  —  temporal, 
masseter,   buccinator,   two 
pterygoids  

Trigeminal  or  5th 

The  digastric  assists  in  mas- 
tication 

5th  and  7th 

Of    the   orbit  —  inferior    ob- 
lique, levator  palpebrae,  su- 
perior rectus,  inferior  rectus, 
internal  rectus  

Oculo-motor,  or  3d. 

external  rectus 

Abducens  or  6th 

superior  oblique  . 

Trochlear,  or  4th. 

Neck,  lateral  

S  terno-mastoid. 

Neck,  posterior  

Trapezius  

S.  accessory  or  nth. 

Neck,  anterior  

Ribbon    muscles,    also     the 
tongue  . 

Hypo-glossal  or  i2th 

Pharynx. 
Larynx. 
Esophagus  

Vatrus  or  loth 

Pharynx  and  Larynx 

Have  also  fibers  from  

Glosso-pharyngeal,   or 

9th. 

Certain  associated  movements  of  the  orbital  muscles  are  of  interest. 
The  central  connections  are  so  arranged  that  the  external  rectus 
of  one  eye  and  the  internal  rectus  of  the  other  move  together; 


CEREBRAL   LOCALIZATION 

both  eyes  turn  in  the  same  direction — right  or  left.  The  two 
internal  recti,  guided  by  a  convergence  nucleus,  act  together  when 
the  eyes  are  directed  toward  a  near  object.  At  the  same  time 
the  pupil  narrows  and  the  ciliary  muscle  seeks  to  adjust  the 
range  of  vision  (see  p.  338). 


FUNCTIONS  OR  PHYSIOLOGY  OF  THE  BRAIN  AND 
CRANIAL  NERVES 

The  cerebrum  presides  over  all  conscious  acts,  and  recognizes 
all  sensations.  The  anterior  portion  of  the  frontal  lobes  is  said 
to  be  the  region  of  mental  activity  or  the  seat  of  the  intellect. 


CONCRLTE   CONCEPT 

FIG.  200. — THE  AREAS  AND  CENTERS  OF  THE  LATERAL  ASPECT  OF  THE  HUMAN 
HEMICEREBRUM.— (C.  K.  Mitts.) 

The  cerebrum  not  only  is  the  seat  of  volition,  directing  the 
purposive  movements  of  the  body,  but  it  also  exerts  a  controlling 
force,  both  accelerating  and  inhibitory,  upon  many  reflex  acts 
which  originate  as  involuntary  in  their  nature.  The  partial  con- 
trol of  respiratory  movements  has  been  already  alluded  to;  laugh- 
ing, weeping,  micturition,  defecation,  and  many  other  acts  may  be 
included  in  the  same  class. 

Cerebral  Localizations. — Connections  between  cortical  areas 
and  certain  parts  of  the  body  have  been  noted,  and  their  control 


312  ANATOMY  AND   PHYSIOLOGY 

over  those  parts  has  been  demonstrated  (Figs.  200,  202).  Among 
them  are  the  centers  for  face  muscles  and  for  the  upper  extremity,  in 
the  anterior  central  convolution;  the  centers  for  articulate  speech 
in  the  lower  convolutions  of  the  frontal  lobe.  Likewise  the  centers 
for  the  special  senses  are  fairly  well  known — as  for  vision  and 
memory  in  the  occipital  lobe ;  for  taste  in  temporal;  for  touch  in  the 
parietal;  and  for  hearing  and  smell  in  the  temporal  and  frontal. 

These  centers  are  all  connected  directly  or  indirectly,  by  a 
complicated  system  of  association  fibers  (Fig.  201),  so  that  by  their 
various  impressions  and  nerve  impulses  they  are  constantly  acting 
with  or  upon  each  other. 

Illustration. — The  faculty  of  speech  implies  many  previous 
mental  acts.  The  mind  must  know  and  recall  the  names  of  things 
in  order  to  mention  them;  it  must  have  seen  or  heard  things  in 
order  to  describe  them  and  to  have  learned  the  words  which  ex- 
press these  conceptions.  It  may  do  all  this  and  still  be  silent, 
until  these  many  factors  are  brought  to  work  together  under  the 
influence  of  the  center  for  articulate  speech  which,  as  seen  in  the 
diagram,  is  in  close  connection  with  those  for  the  larynx,  tongue 
and  face  muscles.  It  is  this  center  which  determines  when  these 
muscles  shall  be  used  for  speaking  instead  of  for  other  purposes. 

The  first  use  of  the  faculty  of  speech  probably  represents  the  attempt  to 
reproduce  a  sound;  next  the  impression  of  something  seen,  itself  having  a 
sound  of  its  own  or  a  name.  Gradually  a  feeling  may  come  to  find  expres- 
sion and  so  on  through  the  endless  line  of  impressions  and  memories,  the 
education  of  the  speech-controlling  center  goes  on;  auditory,  visual,  sensory- 
motor  and  other  centers  all  contributing  to  this  end. 

This  is  one  illustration  from  many  which  might  be  cited,  of 
the  value  of  association  fibers.  In  general  terms  it  may  be  stated 
that  the  most  highly  organized  brain  has  the  greatest  number  of 
association  fibers,  whereby  the  intellectual  faculties  of  judgment, 
reasoning  and  the  will  are  developed. 

The  centers  which  govern  skeletal  muscles  belong  to  the  convolutions 
marked  motor  and  cutaneous  in  Figs.  200  and  202.  Tracing  from  below 
upward — the  larynx,  tongue,  face,  hand,  arm  and  shoulder,  foot,  leg  and 
thigh  are  represented  on  the  lateral  surface,  in  the  central  convolutions  border- 
ing the  Rolandic  fissure;  while  other  thigh  centers  and  those  for  trunk,  are 
found  on  the  medial  surface  bordering  the  longitudinal  fissure. 

Note  that  a  large  portion  of  the  cortex  is  devoted  to  complex 


THE    CEREBELLUM 


aQ  tivities  based  upon  mental  pursuits  and  the  acts  or  states  of 
mind  connected  with  them. 

Clinical  notes. — These  several  localizations  furnish  a  guide  to  the  under- 
standing of  various  disturbances  of  the  nerve  system,  since  irritation  of  a 
given  area  may  cause  disordered  muscle  action  in  the  part  which  it  controls, 
or,  by  pressure  (as  in  hemorrhage  or  apoplexy]  the  power  of  motion  may  be 
lost  (paralysis).  The  same  symptoms  may  follow  softening  of  the  cerebral 
tissue,  the  growth  of  tumors,  etc.  By  carefully  observing  the  condition  of 
the  muscles  affected,  one  can  often  determine  the  location  of  a  brain  lesion. 
Disturbances  of  hearing,  vision,  sensation,  etc.,  likewise  indicate  the  seat  of 
disease  or  injury. 


FIBRES  PROPRI& 


SUPERIOR  LONGITUD- 
INAL FASCICULUS 
STRIA  TERMINALS       \ 
OF  THALAMUS 


CINGULUM 


UNCINATE 
FASCICULUS 

INFERIOR  LONGITUDINAL  FASCICULUS 

FIG.  201. — ASSOCIATION  FIBERS. — (Morris.} 

The  function  of  the  cerebellum  is  to  associate  or  coordinate 
the  actions  of  muscle-groups  for  the  accurate  performance  of 
special  movements.  This  is  most  conspicuously  shown  in 
maintaining  the  equilibrium  of  the  body,  whether  standing  or 
walking.  Injury  to  the  cerebellum  results  therefore  in  vertigo 
and  dizziness,  in  loss  of  the  power  to  keep  one's  balance,  and  of  the 
ability  to  walk  without  staggering. 

The  medulla  oblongata  contains  many  important  governing 
centers.  Among  them  are  the  circulatory  and  the  respiratory 
centers;  these  are  situated  near  each  other  and  together  they 


314  ANATOMY  AND   PHYSIOLOGY 

constitute  the  "vital  knot."  Consequently  this  part  of  the  nerve 
system  presides  over  processes  of  the  body  which  are  necessary 
to  life  itself,  and  when  one  remembers  that  the  motor  and  sensory 
fibers  which  connect  the  brain  and  cord  all  pass  through  the 
medulla,  it  is  easy  to  understand  that  injury  here  produces  far- 
reaching  results. 

The  pons  varolii  is  associated  with  the  medulla  in  its  cranial 
nerve  connections;  most  of  its  fibers  are  conducting  paths  between 
the  other  parts  which  lie  in  the  cranial  cavity. 


FIG.  202. — THE  AREAS  AND  CE.NTERS  OF  THE  MESIAL  ASPECT  OF  THE  HUMAN 
HEMICEREBRUM.— (C.  K.  Milk.} 

The  cranial  nerves  connect  parts  of  the  head  and  face,  also 
certain  muscles  of  the  neck,  with  the  brain.  Through  the  vagus 
(or  pneumogastric)  nerve — the  heart,  lungs  and  digestive  organs 
possess  cranial  connections. 

The  vagus  nerve  and  action  of  the  heart.— The  nerve  muscle 
action  of  the  heart  is  peculiar  to  itself  both  in  structure  and 
function.  The  fibers  of  its  tissue,  or  myocardium,  are  without 
sarcolemma  and  entirely  involuntary  in  action.  Again,  although 
involuntary,  they  are  striped]  they  are  also  short,  broad  and 
branched  to  form  a  inuscle  network — just  such  a  structure 
as  will  insure  vigorous  action  within  a  limited  range  of  motion. 
This  action  is  probably  to  a  large  degree  independent,  since 


THE  VAGUS  NERVE  AND  RESPIRATION          315 

the  heart  possesses  ganglionic  centers  in  its  own  substance  from 
which  it  is  supplied  directly  with  nerve  force.  This  rhythmic 
and  apparently  independent  action  is  regulated  by  the  inhibiting 
or  restraining  influence  of  the  vagus  nerve  upon  the  cardiac  nerves. 
When  from  any  cause  the  heart  is  over-stimulated  the  vagus 
fibers  of  the  cardiac  plexus  slow  it  down,  thus  guarding  it  from  the 
exhaustion  which  follows  overwork.  The  vagus  also  inhibits 
over-action  of  the  vaso-constrictors  preventing  excessively  high 
blood  pressure.  Therefore,  it  is  an  important  agent  for  preserving 
the  balance  of  force  to  be  exerted  between  the  heart  and  blood- 
vessels. 

The  vagus  and  the  process  of  respiration. — This  process  is 
modified  by  the  vagus  nerve,  probably  through  its  influence  upon 
the  respiratory  center  in  the  brain.  The  digestive  organs  (from 
pharynx  down)  contain  vagus  fibers;  their  function  is  not  perfectly 
understood,  they  are  probably  sensory. 


CHAPTER  XXII 

THE  SYMPATHETIC  DIVISION  OF  THE  NERVE 
SYSTEM 

We  have  thus  far  considered  those  nerve  actions  which  are 
associated  with  consciousness,  Although  some  may  be  performed 
in  a  purely  reflex  manner,  all  may  be  exercised  voluntarily. 

The  Sympathetic  Division  is  concerned  with  involuntary 
processes  only.  Nerve  stimulus  between  the  central  nerve  system 
and  internal  organs,  and  to  all  involuntary  muscle  fibers,  is  con- 
veyed through  sympathetic  nerves. 

The  nerve  tissues  of  this  division  are  mostly  gray,  a  large 
majority  of  the  fibers  being  non-medullated,  that  is,  they  have  no 
white  sheath.  This  division  of  the  nerve  system  consists  of  many 
ganglia  connected  together  with  nerve  trunks,  and  of  nerves  which 
connect  the  ganglia  with  various  organs. 

About  twenty- two  pairs  of  sym- 
pathetic  ganglia  are  arranged  in  two 
chains  situated  at  the  sides  of  the 
vertebrae,  and  connected    below  in 
front  of  the  coccyx.     These  are  the 
FIG.  203.— TERMINATIONS  OF    vertebral  or  central  ganglia  (Fig.  204). 
NERVE-FIBRES    IN    THE    GLAND-  The  pre-vertebral  ganglia  are  situ- 

A.  Cells  of  the  parotid  gland  of  ated  in  tne  cavities  of  the  body— 

a  rabbit.    B   Cells  of  the  mam-  thoracic,  abdominal  and  pelvic;  these 
mary  gland  of  a  cat  in  gestation. 

—(Doyon  and  Morat.}  are  intimately  connected   with  the 

viscera. 

The  vertebral  ganglia  are  named  according  to  their  location. 
They  are  cervical,  thoracic,  lumbar,  sacral  and  coccygeal.  They 
all  receive  communicating  branches  from  spinal  nerves,  and  send 
gray  fibers  to  join  spinal  nerves  and  enter  the  spinal  cord.  (Gray 
and  white  communicating  branches  or  rami  communicantes .) 

The  branches  or  nerves  belonging  to  these  various  ganglia  in- 
terlace in  close  networks,  forming  plexuses  which  follow  the  course 
of  arteries,  supplying  their  walls  and  the  viscera  to  which  they 
run.  They  also  supply  the  cells  of  glands. 

316 


SYMPATHETIC   GANGLIA 


317 


CERVICAL 
PLEXUS 


Spinal  accessory  nerve 


J  SUPERIOR  CERVICAL 
<  GANGLION  OF  8YM- 
I  PATHETIO 


MIDDLE  CERVI- 
CAL GANGLION 


..    INFERIOR   CERVI- 
CAL GANGLION 


LUMBAR    GANGLIA 


FIG.  204. — LEFT  SYMPATHETIC  GANGLIA  SHOWING  COMMUNICATIONS  WITH  SPINAL 

NERVES.— (Testut.) 


318  ANATOMY   AND   PHYSIOLOGY 

Special  branches  from  cervical  ganglia  accompany  arteries  to 
the  head,  larynx,  pharynx,  thyroid  body,  and  heart. 

Special  branches  from  thoracic  ganglia  accompany  arteries  to 
lungs  and  esophagus  in  the  thorax;  stomach,  liver,  spleen,  and 
other  viscera  in  the  abdomen.  (The  branches  passing  through  the 
diaphragm  to  the  solar  plexus  and  abdominal  viscera  are  called 
splanchnic  nerves — three  on  each  side.) 

Special  branches  from  lumbar  ganglia  accompany  arteries  to 
kidneys  and  pelvic  organs. 

Special  branches  (or  nerves)  from  the  sacral  ganglia  accompany 
arteries  to  the  pelvic  organs. 

The  most  important  plexuses  are  the  cardiac  and  the  pulmon- 
ary in  the  thorax,  the  celiac  (solar)  in  the  abdomen,  and  the  hypo- 
gastric  in  the  pelvis  (Fig.  205). 

The  cardiac  plexus  lies  underneath  and  behind  the  arch  of  the 
aorta.  Its  branches  supply  the  heart  and  lungs,  following  the 
coronary  and  pulmonary  arteries. 

The  celiac  (or  solar)  plexus  is  in  the  abdomen,  in  front  of 
the  aorta,  at  the  beginning  of  the  celiac  artery.  It  contains  two 
large  ganglia — the  right  and  left  celiac  (semilunar)  ganglia.  This 
plexus  controls  the  vessels  and  the  muscular  coats  of  the  abdominal 
viscera;  it  has  been  called  the  abdominal  brain.  Thus  it  may  be 
understood  how  a  severe  blow  over  the  plexus  would  produce  a 
very  widespread  and  serious  result. 

The  hypo-gastric  plexus  is  in  front  of  the  fifth  lumbar  vertebra 
and  divides  to  form  the  right  and  left  pelvic  plexuses,  which  are 
distributed  to  all  of  the  pelvic  viscera  (along  with  branches  from 
the  sacral  ganglia  and  lumbar-spinal  nerves). 

Notes. — Cardiac  nerves  from  the  cervical  ganglia  descend  to  the  thorax, 
entering  the  cardiac  plexuses  and  supplying  the  heart  and  lungs.  Certain 
branches  from  the  thoracic  ganglia  form  splanchnic  nerves  which  descend  to 
the  abdomen,  entering  the  celiac  plexus  and  celiac  ganglia,  and  supplying 
digestive  organs.  Certain  nerves  from  the  lumbar  ganglia  descend  to  the 
hypo-gastric  plexus  to  enter  the  pelvic  plexuses,  supplying  pelvic  organs. 


FUNCTIONS  OR  PHYSIOLOGY  OF  THE  SYMPATHETIC 

NERVES 

The  work  of  organs  supplied  with  sympathetic  nerves  is  per- 
formed involuntarily  and  unconsciously  save  in  its  results.     Vis- 


SYMPATHETIC   PLEXUSES 


319 


Gtroical  nerve 


*  Otic  ganglion 

-/ Connections  with  Vagus  £  Glotso-pJiajyngeal 
to  form  f/iaryngeal  plexus. 

Submafillary  ganglion. 


,  Connections  with  Vaou.s  and 

Recurrent  laryngeal  nerves. 


">  Xeft Pulmonary  plexui 

CARDIAC  PLEXUS 


Middle     \  Cardiac  nerves 
f  Inferior 


*v  Abdominal  Aortic  plexu» 


mpocAsmic  PLEWS 

Coccygeal  neroe 

Ganglion  Coccygeum  impar 

FIG.  205.— PRINCIPAL  GANGLIA  AND  PLEXUSES  OF  THE  SYMPATHETIC  SYSTEM.— 

(Morris.) 


320  ANATOMY   AND   PHYSIOLOGY 

ceral  muscles,  secreting  cells,  vessel  walls,  are  all  under  the  immediate 
domain  of  the  sympathetic  ganglia  and  nerves,  whose  motor  and 
sensory  fibers  are  parts  of  the  great  nerve  system  of  the  body, 
through  communicating  branches. 

Certain  facts  indicate  a  communication  between  the  brain  and 
sympathetic  nerves,  for  instance,  the  thought  of  food  causes  a  flow 
of  saliva;  think  of  a  lemon — salivary  cells  are  stimulated.  Fright 
or  anxiety  may  inhibit  or  prevent  the  secretion  of  saliva;  or  inter- 
fere with  digestion  through  a  similar  effect  upon  other  digestive 
fluids;  and  it  is  well  known  that  the  secretion  of  milk  is  greatly 
modified  by  mental  or  emotional  influences. 

So  with  general  mso-motor  action.  We  all  know  the  blanched 
face  of  fright  or  mental  shock;  the  flush  of  joyous  excitement;  or 
the  blush  of  embarrassment.  All  of  these  are  sympathetic  reflexes 
of  psychic  origin.  In  the  case  of  secretion  of  digestive  fluids,  the 
psychic  flow  follows  the  thought  of  food  at  once;  after  that  comes 
the  secretion  caused  by  the  presence  and  contact  of  food  in  the 
different  parts  of  the  alimentary  tract. 

Again  the  effect  of  vaso-motor  action  may  be  seen  when  intense 
cold  is  applied  to  the  skin.  The  cutaneous  vessels  contract,  the 
blood  is  driven  out,  the  skin  becomes  white.  The  opposite  condi- 
tion is  caused  by  heat — the  vessels  dilate,  the  blood  flows  in  and 
the  skin  is  red. 

By  alternate  action  of  the  two  kinds  of  vaso-motor  nerves 
(vaso-dilators  and  vaso-constrictors) ,  the  blood  supply  is  adapted  to 
special  and  varying  needs  of  different  parts  of  the  body,  and  the 
balance  of  pressure  preserved  in  their  vessels. 

When  an  organ  has  work  to  perform  its  vessels  dilate  and  the 
necessary  blood  is  supplied.  When  the  work  is  finished  the  vessels 
return  to  their  usual  size  (their  vessel  tone  being  restored  by  vaso- 
constrictors). 

The  process  of  digestion,  for  example,  requires  that  there  should 
be  much  blood  in  many  organs;  the  same  is  true  of  general  muscular 
exercise.  Consequently,  to  exercise  violently  after  a  full  meal  is  a 
mistake,  because  the  muscles  would  deprive  the  digestive  organs 
of  the  extra  blood  which  they  need,  and  an  attack  of  indigestion 
might  follow;  at  best,  digestion  would  be  delayed.  It  would  be 
better  to  delay  the  exercise. 

Many  examples  might  be  given  and  will  probably  occur  to  the 


FUNCTIONS   OF   NERVOUS   SYSTEM  321 

mind  of  the  student,  of  the  interactions  of  different  parts  of  the 
sympathetic  system. 

These  are  the  processes  which  must  go  on  more  or  less  continu- 
ously. Some  may  be  suspended  temporarily,  as  gland  secretions, 
or  digestion,  or  the  formation  of  excretions,  but  they  never  entirely 
cease  without  causing  the  death  of  the  individual. 

SUMMARY 

The  sympathetic  nerves  supply  all  involuntary  muscles,  the 
coats  of  blood-vessels  and  the  cells  of  secreting  glands.  They  are 
the  nerves  of  unconscious  life,  as  the  cerebro-spinal  nerves  are  the 
nerves  of  voluntary  and  conscious  life. 

SUMMARY  OF  THE  FUNCTIONS  OF  THE  NERVE  SYS- 
TEM AS  A  WHOLE 

We  have  now  concluded  the  study  (briefly)  of  the  entire  nerve 
system,  and  we  have  seen  how  intimately  its  various  parts  are  con- 
nected. Only  through  a  knowledge  of  these  connections  can  the 
functions  of  the  system  be  understood. 

It  must  be  remembered  that  all  parts  of  the  head  and  body 
have  at  least  two  central  representations. 

Sensory  nerves  (representing  visceral  muscle,  certain  mucous 
membranes,  etc.,  and  sense  organs),  enter  the  cord  and  proceed  as 
far  as  the  posterior  horns,  whence  another  cell  body  and  its  axon 
receive  and  carry  the  impulse  to  the  cortex  of  the  brain. 

Motor  cortical  cells  of  the  brain  prolong  their  axons  (nerve  fibers) 
only  as  far  as  the  cord  (the  medulla  oblongata  is  the  upper  portion 
of  the  cord).  There  they  meet  certain  other  cells  in  the  anterior 
horns,  where  their  message  is  taken  to  be  carried  by  these  second 
axons  to  skeletal  muscles. 

Different  parts  of  the  spinal  cord  are  associated  one  with 
another  by  conduction  fibers,  and  the  cord  is  connected  with  the 
brain  above  by  many  more,  running  upward  or  downward  through 
the  medulla  and  pons.  (On  the  inferior  surface  of  the  brain  we 
see  these  fibers  as  crura  or  peduncles  of  the  cerebrum  and  cere- 
bellum; they  are  finally  connected  with  the  gray  cells  of  the 
cortex.) 

21 


322  ANATOMY   AND    PHYSIOLOGY 

In  the  spinal  cord  and  Us  nerves  we  find  the  apparatus  for  reflex 
action  which  appears  in  so  many  phases — as  muscle  contraction, 
muscle  tone,  vessel  tone,  etc.  The  spinal  cord,  then,  is  a  great 
reflex  center,  a  conducting  pathway,  and  an  organ  of  coordination  of 
skeletal  muscles. 

Included  in  the  medulla  are  centers  for  still  more  important 
re/Zexes:  the  respiratory  center;  the  cardiovascular  center  or  center 
for  heart-action  and  vessel  tone  combined;  the  heat  regulating 
center;  deglutition  center,  and  others.  Certain  functions  which 
these  centers  control  may  be  modified  by  the  will;  for  example, 
the  respiratory  act — we  may  take  a  long  full  breath  or  a  short  and 
shallow  one;  breathe  rapidly  or  slowly,  at  will.  Deglutition  is  still 
nearer  to  the  realm  of  voluntary  movements — only  when  food 
reaches  the  esophagus,  is  the  act  of  deglutition  purely  reflex.  (Here 
is  the  first  appearance  of  unstriped  muscle  in  the  digestive  tract.) 

Going  higher  we  find  the  cerebellum  presiding  over  the  coordi- 
nation of  conscious  and  voluntary  movements,  through  its  connec- 
tion with  the  cortex  of  the  cerebrum  on  one  hand,  and  the  pons, 
medulla  and  cord  on  the  other.  Also  upon  the  cerebellum  depends 
the  maintenance  of  body  equilibrium.  For  this  it  is  necessary  that 
the  semicircular  canals  of  the  internal  ear  should  be  normal  and  in 
perfect  connection  with  the  cerebellum.  Other  sensory  connec- 
tions also  contribute  to  the  exercise  of  this  function;  for  example, 
to  walk  unaided  without  vision  is  possible,  but  not  in  a  straight 
line;  or,  to  walk  with  feet  benumbed  is  difficult,  more  so  to  stand 
motionless;  showing  that  the  cerebellum  is  stimulated  to  the 
coordination  by  which  equilibrium  is  maintained,  by  more  than 
one  sort  of  stimulus,  probably  by  many. 

We  balance  the  body  in  equilibrium  without  conscious  sensa- 
tion unless  we  voluntarily  direct  our  attention  to  the  subject.  It 
is  the  disturbance  of  equilibrium  which  we  feel. 

Going  still  higher,  we  find  in  the  cerebrum  the  perfecting  of 
the  plan  for  bringing  the  whole  sentient  and  moving  organism  into 
the  domain  of  consciousness  and  the  will.  This  is  by  means  of 
the  connections  of  the  cerebrum  through  the  pons,  medulla,  and  cord 
and  their  nerves,  with  every  part  of  the  body  from  which  afferent 
impulses  come,  and  to  which  efferent  impulses  may  be  transmitted. 

The  importance  of  these  connecting  fibers  cannot  be  over- 
estimated; without  them  the  body  would  be  a  disjointed  affair. 


NERVES  OF  SKELETAL  MUSCLES 
C.S.C. 


323 


-$. 


FIG.  206. — DIAGRAM  SHOWING  THE  RELATION  OF  SKELETAL,  MUSCLE  AND  NERVE 

TISSUES  — (G.  Bachman.) 

f.a.  Bones  of  the  forearm  representing  the  skeletal  tissue;  e.j.  the  elbow 
joint,  the  fulcrum  of  the  lever  formed  by  the  bones  of  the  forearm;  W.  a 
weight  acting  in  a  downward  direction  and  representing  the  passive  force  of 
gravity;  sk.m.  a  skeletal  muscle  acting  in  an  upward  direction  and  the  source  of  the 
active  power  to  be  applied  to  the  lever;  sp.c.  transection  of  the  spinal  cord  showing 
the  relation  of  the  white  and  the  gray  matter;  m.c.  a  motor  cell  in  the  anterior  horn 
of  the  gray  matter;  ef.n.  an  efferent  nerve-fiber  connecting  the  motor  cell  from  which 
it  arises  with  the  skeletal  muscle  and  contained  in  the  ventral  roots  of  the  spinal 
nerves;  af.n.  an  afferent  nerve-fiber  arising  from  the  ganglion  cell  along  its  course  and 
connecting  the  skin,  s.,  on  the  one  hand  with  the  spinal  cord  on  the  other  hand  and 
contained  in  the  dorsal  roots  of  the  nerves;  c.s.c.  coronal  section  of  the  cerebrum 


324  ANATOMY   AND   PHYSIOLOGY 

Concerning  the  reception  and  originating  of  ideas,  the  exercise 
of  thinking — in  other  words,  intellectual  processes — we  know 
only  that  these  activities  certainly  depend  for  their  normal 
manifestation  upon  a  normal  cerebrum.  A  well-developed  cere- 
brum has  good  convolutions  and  deep  furrows,  and  white  fibers 
in  good  connection  with  its  several  parts.  These  indicate  mental 
power,  being  of  more  importance  than  the  mere  size  of  the  brain. 
The  brain  of  the  infant  possesses  all  of  the  interior  parts,  as 
ganglia,  etc.,  but  the  cortex  is  almost  smooth.  The  cortical  cells 
are  immature  and  many  axons  have  not  become  sheathed.  With 
the  growth  of  the  child  and  quickening  of  the  mind,  the  convolu- 
tions and  furrows  appear  and  develop;  the  cortical  cells  mature 
and  the  white  fibers  become  sheathed.  (The  brain  fiber  does  not 
conduct  impulses  before  its  sheath  is  complete.) 

The  number  of  association  fibers  (Fig.  201)  is  an  index  of  the 
mental  power  of  a  brain.  Large  association  areas  signify  a  large 
expanse  of  cortex  with  power  to  register,  remember  and  compare 
a  multitude  of  sensations  from  various  sources — and  the  ability 
to  reason  about  them  and  form  opinions  concerning  them. 

The  sympathetic  division  of  the  nerve  system  is  the  medium 
of  communication  (through  communicating  branches)  of  nerve 
impulses  between  the  cerebro-spinal  system  and  the  organs  con- 
cerned in  involuntary  processes,  notably  those  connected  with 
nutrition  and  growth,  through  control  of  secreting  cells  and  vessel 
tone. 

showing  the  relation  of  the  gray  to  the  white  matter;  v.c.  a  volitional  or  motor  cell; 
d.a.  a  descending  axon  or  nerve-fiber  connecting  the  volitional  cell  from  which  it 
arises  with  the  motor  cell  in  the  spinal  cord;  s.c.  a  sensor  cell;  a.a.  an  ascending  axon 
or  nerve-fiber  connecting  a  receptive  cell  from  which  it  arises  (not  shown  in  the  dia- 
gram) with  the  sensor  cell  in  the  gray  matter  of  the  cerebrum.  The  nerve-fibers 
which  pass  outward  from  the  spinal  cord  to  the  glands,  blood-vessels,  and  the 
muscle  walls  of  the  viscera,  have  for  the  sake  of  simplicity  been  omitted  from  the 
diagram. 


CHAPTER  XXIII 

THE  SPECIAL  SENSES 

GENERAL  SENSATION 

In  studying  the  structure  and  functions  of  the  nerve  system, 
we  learn  that  sensory  stimuli  are  received  in  every  part  of  the  body 
by  afferent  nerves,  and  conducted  to  sensory  cells  in  the  spinal 
cord ;  there  they  either  evoke  a  muscle  response  of  reflex  character, 
or  are  transmitted  by  connecting  tracts  to  the  brain,  where  the 
result  is  conscious  sensation  of  some  sort:  as,  for  example,  of  tem- 
perature— whether  of  the  surrounding  air,  or  of  bodies  which  we 
touch;  or  of  other  conditions — whether  an  object  is  hard  or  soft, 
wet  or  dry,  rough  or  smooth,  etc.,  etc.  These  are  common  and 
definite  sensations  of  external  things  and  by  these  external  sensa- 
tions we  gain  knowledge  of  the  world  about  us.1 

Others  there  are  which  are  definable  in  general  terms  only, 
and  are  not  definitely  located,  although  plainly  felt.  For  in- 
stance, we  are  hungry,  or  thirsty,  or  tired;  after  pain  we  have  a 
sense  of  relief,  etc.,  the  route  for  stimulus  and  response  in  these 
matters  is  through  visceral  and  vaso-motor  nerves  and  their 
spinal  and  cerebral  connections,  and  by  these  internal  sensations 
we  gain  acquaintance  with  our  individual  selves.  For  example, 
hunger  is  the  recognition  of  a  lack  of  food  in  the  tissues;  thirst, 
of  a  lack  of  fluid.  Fatigue  is  the  sensation  caused  by  over- 
loading the  tissues  with  waste  products  of  metabolism  (fatigue 
poisons). 

Other  mechanisms  in  the  body  are  adapted  to  a  more  definite 
class  of  sensations,  by  which  we  learn  to  know  still  more  exten- 
sively, the  world  in  which  we  live;  these  are  called  the  organs  of 
the  special  senses. 

1  We  do  not  now  refer  to  cranial  nerves  in  which  the  arrangement  is  similar  but 
more  intricate. 

325 


326  ANATOMY  AND  PHYSIOLOGY 

SPECIAL  SENSATION 

The  special  senses  are:  smell,  touch,  taste,  hearing  and  sight. 
The  organs  concerned  are  the  nose,  the  skin,  the  tongue,  the  ear  and 
the  eye. 

It  is  understood  that  all  consciousness  of  sensation  is  based 
upon  the  final  reception  of  sensory  impressions  by  the  brain.  So 
far  as  a  "  sense "  may  be  said  to  reside  anywhere,  it  resides  in  the 
brain,  for  without  it  there  are  no  senses  as  we  know  them. 

THE  SENSE  OF  SMELL 

The  nose  is  the  organ  of  the  sense  of  smell.  In  the  nasal 
chambers  is  a  layer  of  special  cells — olfactory  cells — supported 
by  a  basement  membrane,  forming  the  Schneiderian  membrane 
(or  pituitary  membrane).  The  upper  part  only  of  the  nose  is 
the  olfactory  region.  Here  the  sensory  nerves  arise  which  proceed 
through  the  foramina  in  the  cribriform  plate  or  the  roof  of  the 
nose,  to  the  brain. 

In  quiet  respiration  most  of  the  air  passes  in  and  out  through 
the  lower  parts  of  the  nasal  chambers,  diffusing  gradually  into  the 
upper  parts.  Although  most  odors  are  readily  perceived  as  soon 
as  one  comes  into  the  atmosphere  containing  them,  a  slight  odor 
is  better  appreciated  by  means  of  an  effort  to  draw  the  air  through 
the  olfactory  region,  in  other  words,  a  sniff.  More  of  the  odorous 
particles  are  thus  brought  into  contact  with  the  olfactory  cells,  and 
the  impressions  made  upon  them  are  transmitted  by  the  delicate 
olfactory  nerves  through  the  cribriform  plate  to  the  olfactory  bulbs 
and  thence  by  the  olfactory  tracts  to  the  olfactory  center  in  the 
temporal  lobe  of  the  brain. 

The  sense  of  smell  is  valued  for  the  pleasurable  sensations 
which  it  affords,  as  an  adjunct  to  the  sense  of  taste,  and  as  a 
sentinel  to  warn  us  of  danger  when  in  the  vicinity  of  irritating  or 
poisonous  gases,  etc. 

Clinical  notes. — It  may  become  greatly  impaired  in  catarrhal  affections 
of  the  nasal  mucous  membrane,  and  is  sometimes  lost  temporarily  or  per- 
manently after  an  attack  of  influenza,  congestion  and  consequent  dryness  of 
the  olfactory  membrane  (as  in  coryza  or  "cold  in  the  head")  always  diminish 
the  acuteness  of  smell.  The  degree  of  development  of  this  sense  in  lower 
animals  is  remarkable;  they  readily  "scent  danger." 


MUSCLE   SENSE 


327 


f«0pffi!BIHHi 


- 
— 


THE  SENSE  OF  TOUCH 

The  skin  and  the  mucous  membrane  of  the  mouth  constitute 
the  organ  of  the  special  sense  of  touch  (all  mucous  membranes 
are  sensitive  to  temperature  and  pain,  but  only  that  of  the  mouth 
is  sensitive  to  touch). 

The  special  nerve  endings  are  situated  in  the  deeper  layers,  in- 
cluding the  hair  follicles,  and  the  papillae.  Upon  their  number 
and  nearness  to  the  surface  depends  the 
acuteness  of  this  sense.  An  area  covered 
by  thick  layers  of  epidermis  is  not  so 
sensitive  as  one  where  it  is  thin;  and  vice 
versa. 

There  are  several  forms  of  nerve  end- 
ings:  tactile  cells,  for  common  sensations, 
found  throughout  the  skin  in  the  deeper 
layers,  hair  follicles,  and  papillae;  touch  cor- 
puscles, also  in  the  papillae  and  especially 
numerous  in  the  palm  and  finger  tips,  where 
sensation  is  particularly  acute;  other  forms 
in  muscles  and  tendons;  others  still,  for  the 
perception  of  heat  and  cold  or  temperature 
sense,  etc.,  etc.  These  all  belong  to  the 

sensory   nerves   of  the  cerebro-spinal  nerve 

^^ 
system. 

The  sense  of  touch  includes  many  va-  & 

rieties  of  impressions  by  means   of  which       FIG.  207.—  TOUCH-COR- 
.     ,  P  ,.  .      PUSCLE  OF  MEISSNER  AND 

we  may  judge  of  surroundings,  and  gain  WAGNER. 

the  necessary  knowledge  concerning  the  b.  Papilla  of  cutis.  d. 
external  world  whereby  we  can  adjust  our-  N-ve-fiber  *»£?£ 
selves  to  its  conditions.  Several  of  these  touch-corpuscles,  g.  Cells 

,,,..,  of     Malpighian     layer.  — 

are  included  in  the  term      muscle  sensa-  (From  Stirling.} 
tions";  they  constitute  the  muscle  sense. 

By  this  we  become  aware  of  many  things,  as  the  direction  of 
movements  of  our  own  bodies,  whether  active  or  passive;  of  the 
postures  of  the  body  or  its  parts;  (this  knowledge  we  apply  to 
the  maintenance  of  balance).  Also,  by  muscle  sense  we  estimate 
the  degree  of  force  felt  by  the  impact  of  a  moving  body,  or  of  a 
blow  received  or  given  (this  last  is  closely  related  to  the  apprecia- 


328  ANATOMY   AND   PHYSIOLOGY 

tion  of  weight).  The  faculty  of  stereognosis  depends  upon  the 
exercise  of  muscle  sense  (it  is  the  recognition  of  articles  by  hand- 
ling them,  thus  awakening  memories  of  objects  previously  known)  . 
Simple  contact  evokes  no  sensation  without  a  certain  degree  of 
pressure;  touch  and  pressure  are  therefore  closely  related;  with 
increased  pressure  comes  the  impression  of  weight.  If  pressure 
is  sufficiently  increased,  pain  will  be  felt,  which 
is  due  to  the  disturbance  of  nerves  more  deeply 
situated. 

Again,  a  touch  imparts  also  a  sensation  of 
place,  the  place  where  it  occurs;  therefore  the 
sense  of  touch  includes  the  place  sense. 

THE  SENSE  OF  TASTE 

F  \  G      2  0  8  _          The  tongue  is  spoken  of  as  the  organ  of  taste, 
TASTE-BUD    FROM  since  it  bears  the  taste  buds.     The  sense  of  taste 

ClRCUMVALLATE  ,  .,..., 

PAPILLA  OF  A  CHILD.  may  De  regarded  as  a  specialization  of  the  sense 
The  oval  struc-  of   touch  and   the  two  mechanisms  somewhat 


ture  is  limited  to  the  rpcPrnhlA 

epithelium  (e)  lining  reS6I] 

the  furrow,   en-         The    nerve    endings    (belonging  to   the   5th 

upon  the  adjacent  an<^  9tn    cranial    nerves)   which  are  developed 

connective   tissue  for  this  purpose  are  scattered  over  the  surface 

(f);    o,     taste-pore 

through  which  the  of  the  tongue,  and  in  (certain  of)  the  papillae, 

-  also  in  the  Palate  and  palatine  arches  (possibly 


cous    surface.—  sometimes  in  the  pharynx).     They  are  found  in 

(A  ]lcY  ilPY^OL    ) 

small  oval  bodies  called  taste  buds,  which  are  in 
direct  connection  with  the  gustatory  nerves. 

In  order  to  excite  the  nerves  of  taste,  substances  must  be  either 
already  in  solution  or  soluble  by  the  saliva;  a  perfectly  dry  sub- 
stance may  be  felt  by  the  tongue,  and  its  temperature,  etc.,  will  be 
appreciated,  but  it  cannot  be  tasted.  Although  all  flavors  may 
be  recognized  in  all  parts  of  the  tongue,  some  are  more  keenly 
appreciated  in  one  portion  than  another;  for  example:  the  bitter 
flavors  are  more  plainly  tasted  in  the  posterior  region,  while  per- 
ception of  sweets  is  more  marked  in  the  anterior  parts.  The  borders 
seem  to  apprehend  acids  more  quickly  than  the  dorsum. 

Touch,  temperature,  and  smell  are  all  associated  with  taste. 
If  a  substance  is  too  hot  the  sense  of  taste  is  overcome  by  the 


THE    EXTERNAL    EAR  329 

sense  of  pain.  Many  people  who  have  been  deprived  of  the  sense 
of  smell  (by  disease  or  injury)  assert  that  they  no  longer  possess 
the  sense  of  taste,  or  that,  if  present,  it  is  greatly  impaired. 

THE  SENSE  OF  HEARING 

The  organ  of  the  sense  of  hearing  is  the  ear.  It  has  three 
divisions:  external,  middle,  and  internal  (Fig.  210). 

The  external  ear  is  that  part  which  is  on  the  outside  of  the 
skull,  it  includes  the  auricle  and  the  auditory  tube.  The  expanded 
portion,  mostly  of  cartilage  covered  with  skin,  is  the  auricle;  the 


Fossa-iirli  -SMi-  Fossa 


Lobule 


FIG.  209. — THE  EXTERNAL  EAR.— (Morris.) 

deepest  depression  is  the  concha,  and  the  opening  at  the  bottom 
of  the  concha  leads  to  the  external  auditory  canal  (or  meatus). 

This  auditory  canal  is  one  and  one-quarter  inches  in  length, 
formed  partly  by  the  cartilage  of  the  auricle  and  partly  by  the 
temporal  bone.  It  curves  slightly  upward,  and  then  downward 
and  forward.  It  is  lined  with  skin  which  bears  stiff  hairs  in  the 
outer  portion,  and  contains  the  glands  which  secrete  "ear  wax" 
(ceruminous  glands).  It  is  important  to  remember  the  length  and 
direction  of  this  canal. 

The  membrane  at  the  end  of  the  canal  is  called  the  membrana 
tympani,  or  membrane  of  the  drum.  It  is  a  fibrous  membrane 


330 


ANATOMY  AND   PHYSIOLOGY 


covered  with  very  sensitive  skin  on  the  outer  surface,  and  mucous 
membrane  within  (Fig.  210). 

The  middle  ear  is  the  tympanum,  or  drum.  It  consists  of  a 
small  cavity  in  the  petrous  bone,  on  the  inner  side  of  the  membrane 
of  the  drum.  Its  height  is  barely  half  an  inch,  and  the  other 
measurements  are  smaller  still.  It  contains  the  little  bones  and 
forms  the  beginning  of  the  auditory  tube. 

The  auditory  (or  Eustachian)  tube  begins  in  the  wall  of  the 
middle  ear  and  ends  as  a  roll  of  cartilage  opening  into  the  pharynx. 

The  tympanum  is  really  an  air  chamber,  since  it  communicates 


S  emicircular 
canals 


Drum  membrane 


Cochlea 
Cavity  of  tym- 
panum   or 
drum 


\ 


Parotid  gland 


Styloid  process 

Internal 
carotid    artery 


Auditory  tube 

FlG.    210.- 


-THE  EAR.— (Morris.) 


with  the  throat  by  the  auditory  (or  Eustachian)  tube,  and  both  tube 
and  tympanum  are  lined  with  a  continuation  of  the  same  mucous 
membrane.  An  opening  at  the  back  of  the  tympanum  leads  into 
the  mastoid  antrum,  and  through  this,  inflammation  of  the  middle 
ear  frequently  extends  to  the  mastoid  cavities. 

Note.— The  mucous  membrane  of  the  pharynx  is  continued 
through  the  auditory  tube  into  the  tympanum,  and  through  that 
into  the  mastoid  cells.  Swelling  of  this  membrane  may  occlude 


THE   INTERNAL   EAR 


331 


the  tube  and  thus  prevent  its  normal  function,  which  is  the  trans- 
mission of  air  to  and  from  the  tympanum  and  the  equalization  of 
air-pressure  on  the  two  surfaces  of  the  tympanic  membrane, 
(the  external  surface  at  the  end  of  the  auditory  canal  and  the 
internal  surface  within  the  tympanum). 

Clinical. — Certain  muscle  fibers  of  the  pharynx  are  so  arranged 
that  in  the  act  of  swallowing  the  auditory  canal  is  opened.  This 
fact  is  taken  advantage  of  in  passing  the  Eustachian  catheter  into 
the  tube. 

Two  openings  lead  from  the  tympanum  to  the  internal  ear— 
the  oval  or  vestibular  window  and  the  round  or  cochlear  window. 

The  round  window  is  closed  by  a  membrane  called  the  secondary  membrane 
of  the  tympanum.  The  oval  window  is  closed  by  a  fibrous  layer  and  the  base 
of  the  stirrup  bone  (p.  333). 


FIG.  211. — BONY  COCHLEA. 

i.  Ampulla  of  superior  semi- 
circular canal.  2.  Horizontal 
canal.  3.  _  Junction  of  superior 
and  posterior  semicircular  canals. 
4.  The  posterior  semicircular 
canal.  5.  Foramen  rotundum. 
6.  Foramen  ovale.  7.  Cochlea. 
—(Brubaker.} 


FIG  212. — i.  Utricle.  2. 
Succule.  3.  Vestibular  end  of 
cochlea.  4.  Canalis  reuniens. 
5.  Membranous  cochlea.  6. 
Membranous  semicircular 
canals. — (Brubaker.} 


The  internal  ear  is  a  cavity  more  deeply  situated  in  the 
petrous  bone.  It  is  extremely  complicated,  consisting  of  semi- 
circular canals,  vestibule,  and  cochlea,  and  well  named  the 
labyrinth.  There  are  three  semicircular  canals  placed  at  right 
angles  to  each  other;  the  cochlea  resembles  a  snail- shell  in  form, 
and  the  vestibule  is  between  them. 

The  cochlea  and  the  vestibule  both  communicate  with  the 
tympanum,  the  cochlea  by  the  round  or  cochlear  window;  the  vesti- 
bule by  the  oval  or  vestibular  window. 

The  illustration  (Fig.  211)  shows  the  shape  of  the  osseous 
labyrinth  cut  from  the  petrous  bone.  Observe  the  three  semi- 


332  ANATOMY   AND   PHYSIOLOGY 

circular  canals  each  with  bulb-like  extremity,  or  ampulla,  opening 
into  the  vestibule.  (Two  are  joined  together  at  one  extremity, 
leaving  five  openings  for  the  three  canals.) 

Observe  the  two  windows,  round  and  oval  in  the  vestibule  wall, 
open  in  the  dried  bone,  as  in  the  illustration,  but  closed  in  life  by 
the  lining  membrane  of  the  internal  ear. 

The  cochlea  is  a  spiral  canal  winding  two  and  one- half 
turns  about  a  central  stem  of  petrous  bone  (the  modiolus).  It  is 
divided  into  three  canals  or  scala,  reaching  from  base  to  apex  of  the 
spiral.  In  one  of  these  the  membranous  cochlea  lies;  of  the  two 
others,  one  opens  into  the  vestibule  and  the  other  ends  at  the 
round  window,  separated  from  the  tympanum  by  the  secondary 
membrane. 

The  internal  ear  has  a  fibro-serous  lining  which  contains  a 
clear  watery  fluid  called  perilymph. 

Lying  in  the  perilymph  and  bathed  by  it  is  the  membranous 
labyrinth  having  all  parts  and  shapes  of  the  osseous  labyrinth. 

Fig.  212  shows  the  membranous  labyrinth  which  lies  within  the 
bony  labyrinth,  surrounded  by  perilymph.  It  contains  a  fluid 
called  endolymph  which  bathes  the  fine  nerve-fibers  of  the  auditory 
nerves. 

Note  the  membranous  semicircular  canals,  with  their  ampullae , 
membraneous  cochlea  and  the  two  portions  of  the  membranous  vesti- 
bule. Within  these  (called  the  saccule  and  utricle),  the  ampullae, 
and  the  cochlea,  the  terminal  fibers  of  the  auditory  nerve  are 
distributed. 

Ossicles. — A  chain  of  three  ossicles  (or  little  bones)  is  sus- 
pended across  the  tympanum — the  malleus,  incus,  and  stapes. 
The  malleus  (ox  hammer)  is  attached  by  the  handle  to  the  membrane 
of  the  drum,  the  incus  (or  anvil)  comes  next,  and  then  the  stapes 
(or  stirrup)  with  its  base  fitting  the  oval  window  of  the  middle  ear. 
Any  vibration  of  the  membrane  of  the  tympanum  is  at  once  trans- 
mitted by  this  chain  of  bones  across  the  tympanum,  to  the  oval 
window. 

The  base  of  the  stapes  occupies  the  oval  window  (fenestra  ovalis); 
its  movements  are  transmitted  to  the  perilymph  and  through  this 
to  the  membranous  labyrinth,  thence  to  the  endolymph  within  it 
and  the  auditory  nerves. 


AUDITORY   NERVES  333 

Nerves  of  the  internal  ear. — There  are  two  distinct  mech- 
anisms in  the  internal  ear;  one  for  the  sense  of  hearing,  the  other 
to  serve  as  an  organ  of  equilibration.  So  there  are  two  separate 
nerves,  included  under  the  one  name — auditory.  Both  are 
auditory  in  the  sense  of  being  connected  with  the  ear;  both  are 
purely  sensory  and  both  are  called  into  action  by  the  stimulus  of 
mechanical  vibration,  but  here  the  likeness  ends.  They  differ 
in  their  terminals  and  their  central  connections.  We  shall  speak  of 
them  as  the  cochlear  nerve  and  the  vestibular  nerve. 

The  cochlear  nerve  is  the  true  nerve  of  hearing.  Its  terminal 
fibers  are  found  in  highly  specialized  epithelial  cells  in  the  mem- 
branous cochlea  (and  one  ampulla) ;  there  they  receive  impres- 
sions transmitted  by  the  vibrating  chain  of  bones. 

By  these  fibers  the  cochlear  nerve 

is  formed.     It  passes   through  the  llICutf^«Mr    UMALLEUS 

internal    auditory    canal    into    the 
cranial  cavity  and  disappears  in  the 
medulla.     Its  fibers   end  in  nuclei 
situated  in  the  medulla,  from  which   STAPES 
the  impressions  brought   by  them 
are  conveyed  finally  to  the  auditory 
area  in  the  temporal  lobe  (superior  FIG.  213.— BONES  OF  THE  EAR.— 
temporal  convolution). 

The  terminal  fibers  of  the  vestibular  nerve  are  found  in 
the  special  cells  within  the  membranous  vestibule  and  ampulla  of 
the  semicircular  canals.  From  thence  they  are  gathered  to  form 
the  nerve;  it  leaves  the  petrous  bone  in  company  with  the  cochlear 
nerve  and  enters  the  medulla.  The  cortical  centers  for  this  nerve 
are  in  the  cerebellum.  It  is  not  concerned  in  hearing  but  is  neces- 
sary to  the  power  of  preserving  equilibrium  in  standing,  walking, 
etc.  The  person  in  whom  this  nerve  has  been  destroyed  cannot 
walk  steadily  and  is  not  subject  to  seasickness. 

The  vestibular  nerve  filaments  are  thought  to  be  stimulated 
when  vibrations  of  the  endolymph  are  caused  by  changes  in  the 
position  of  the  head.  This  seems  to  be  established  clinically. 
Through  wide  association  with  other  nerves,  changes  in  the 
position  of  the  body  also  affect  this  nerve.  The  vestibular  nerve 
fibers  end  in  nuclei  situated  in  the  medulla,  from  which  impressions 
brought  by  them  are  conveyed  to  the  centers  in  the  cerebellum. 


334  ANATOMY  AND  PHYSIOLOGY 

SUMMARY 

The  function  of  the  external  ear  is  to  gather  and  direct  the  sound 
waves  to  the  membrane  of  the  tympanum.  (The  ceruminous 
glands  and  hairs  of  the  auditory  canal  protect  the  membrane  from 
foreign  bodies  floating  in  air  currents.) 

The  function  of  the  middle  ear  or  tympanum  is  to  transmit  the 
vibrations  thus  caused,  by  the  chain  of  bones  to  the  oval  window. 

The  function  of  the  internal  ear  is  to  receive  and  transmit  these 
impressions  to  the  brain  (the  perilymph  and  endolymph  modify 
the  force  of  the  vibrations  as  well  as  transmit  them) .  If  they  are 
received  by  the  cochlear  nerve,  they  are  conducted  to  the  auditory 
area  in  the  temporal  lobe  of  the  cerebrum.  If  by  the  vestibular 
nerve,  they  are  conducted  to  the  cerebellum. 

Associated  nerves  and  functions. — Many  coordinated  move- 
ments are  associated  with  the  sense  of  hearing. 

Listening  causes  a  local  increase  of  tension  in  the  muscles  which 
affect  the  position  of  the  eyes  and  head;  very  intent  listening  is 
accompanied  by  a  steadying  or  stiffening  of  the  skeletal  muscle 
system,  and  also  an  instinctive  slowing  or  stopping  of  respiration. 
A  sudden  noise  at  one  side  causes  an  involuntary  turning  of  the 
head  toward  the  location  of  the  sound. 

The  associations  of  the  vestibular  nerves  are  very  wide.  They 
include  not  only  the  nerves  of  muscles  which  move  the  face  and 
head,  but  the  pneumogastric  or  vagus,  and  centers  in  the  anterior 
and  lateral  tracts  of  the  cord  in  its  whole  length,  whereby  the 
muscle-sense  nerves  of  the  body  are  all  referred  to  the  cerebellum. 
In  this  manner,  many  different  muscle  groups  are  associated  and 
coordinated  in  harmonious  body  movements  which  we  are  under 
constant  necessity  to  perform  in  the  common  activities  of  life. 


CHAPTER  XXIV 


THE  SENSE  OF  SIGHT.     THE  VOICE 

The  eye  is  the  organ  of  sight.  It  is  situated  in  the  orbital 
fossa  resting  in  a  collection  of  adipose  tissue  from  which  it  is 
separated  by  the  capsule  of  Tenon.  This  is  a  thin  fascia  surround- 
ing the  greater  part  of  the  eyeball,  and  making  a  " flexible  pocket" 
or  lymph  space  in  which  the  ball  can  be  freely  moved.  The  eye 
is  a  sphere  or  globe  having  at  its  surface  three  layers  called  the 
coats  .or  tunics  of  the  eye — namely  the  solera  and  cornea  (fibrous) , 
forming  the  outer  coat,  the  choroid  and  iris  (vascular),  forming 
the  middle  coat,  and  the  retina  (nervous) — the  inner  coat.  They 


Retina 


Choroid 


Sclera  — 


Cornea 

Iris 

Ciliary  processes 

Lymph  canal 
Ciliary  muscle 


FIG.  214.— A  SECTION  OF  THE  EYE.— (H olden.) 

i,  Anterior  chamber;  2,  posterior  chamber.     The  aqueous  humor  occupies  the  two 

chambers. 

contain  three  transparent  structures — the  aqueous  humor,  crystal- 
line lens  and  vitreous  body. 

The  sclera  is  the  "white  of  the  eye."  It  is  dense  and  tough, 
protecting  the  more  delicate  structures  within.  One-sixth  of  the 
surface  of  the  ball  in  front  is  occupied  by  the  cornea  instead  of 
the  sclera,  and  this  also  is  dense  and  tough,  but  transparent  for 
the  admission  of  light.  It  contains  no  blood-vessels,  but  many 
tiny  lymph-spaces.  It  is  the  most  prominent  part  of  the  eyeball, 

335 


336  ANATOMY   AND   PHYSIOLOGY 

and  its  convexity  may  be  seen  by  looking  across  an  eye  from  the 
side.  The  junction  of  the  cornea  with  the  sclera  resembles  the 
fitting  of  a  watch-crystal  in  its  case. 

The  portion  of  the  sclera  which  is  visible  when  the  eyelids  are 
separated,  and  also  the  cornea,  are  both  covered  by  a  thin  mem- 
brane called  the  conjunctiva;  it  is  a  modified  mucous  membrane, 
bearing  blood-vessels  which  can  be  seen,  especially  if  a  little 
dilated. 

The  choroid. — The  middle  coat,  next  to  tne  sclerotic,  is  neither 
dense  nor  tough,  but  is  made  up  of  fine  tissue  fibers  bearing  a 
very  delicate  and  close  network  of  blood-vessels.  It  is  the  vascular 
coat  of  the  eye,  and  lines  the  sclera  only,  not  the  cornea.  Many 
pigment  cells  are  contained  in  the  choroid  coat,  giving  to  it  a 
deep  brown  color  so  that  it  makes  a  dark  chamber  of  the  eye. 


Sclera 


FIG.  215. — THE  CHOROID  AND  IRIS. — (H olden.} 

The  iris. — There  is  no  choroid  behind  the  cornea.  Its  place 
is  supplied  by  the  iris,  which  resembles  in  its  shape  a  circular 
curtain  attached  by  its  edge  to  the  choroid,  and  having  a  round 
aperture  in  the  center  called  the  pupil  or  the  "star  of  the  eye." 
The  iris  contains  a  network  of  fine  vessels  and  pigment  cells, 
varying  in  color  according  to  the  amount  of  pigment.  (Blue  eyes 
have  least,  black  eyes  most.)  It  has  muscular  fibers  arranged  in 
two  sets — circular,  or  ring  fibers,  and  so-called  radiating,  or  straight 
fibers.  The  circular  fibers  surround  the  pupil.  Thus,  when  they 
contract,  as  in  a  bright  light,  they  diminish  its  size.  The  straight 
fibers  run  from  the  outer  border  of  the  iris  toward  the  pupil,  and 


THE    OPTIC   NERVE  337 

therefore  when  they  contract  they  draw  upon  the  margin  to  enlarge 
the  opening.  Briefly,  the  pupil  is  contracted  by  the  circular  fibers, 
and  dilated  by  the  straight  or  radiating  fibers,  thus  the  amount  of 
light  admitted  within  the  eye  is  regulated. 

The  retina  is  the  innermost  coat,  of  many  layers,  within  the 
choroid.  This  is  a  very  delicate  structure  in  which  are  the  be- 
ginnings of  the  optic  nerve  fibers.  It  is  the  coat  which  is  essential 
to  vision — no  retina,  no  vision.  The  outermost  layer  of  the  retina 
is  the  one  which  contains  the  rods  and  cones,  or  the  visual  cells. 
Like  the  sclera  and  choroid,  the  retina  is  incomplete  in  front. 
When  first  exposed  to  the  air  (in  the  dissection  of  an  eye)  it  is 
clear  and  shining  in  appearance,  presenting  an  opalescent  play 
of  color  with  a  general  violet  tinge,  due  to  the  "visual  purple" 
contained  in  delicate  pigment  cells. 

From  the  cells  in  the  retina  delicate  fibers  are  prolonged  and 
gathered  together  to  form  the  optic  nerve,  which  pierces  the 
choroid  and  the  sclerotic,  passes  through  the  optic  foramen  of 
the  orbit,  and  thence  back  to  the  brain.  The  optic  disc  is  the  spot 
where  the  optic  nerve  leaves  the  retina;  it  is  situated  a  little  to  the 
nasal  side  of  the  center  of  the  retina  (Figs.  214,216).  Of  course  the 
optic  disc  is  not  a  portion  of  the  retina  proper,  and  no  sense  of 
vision  is  stimulated  here.  It  is  rather  an  area  where  the  nerves 
and  vessels  are  transmitted  through  the  other  coats  of  the  eyeball. 

The  macula  lutea  is  a  spot  in  the  center  of  the  retina  opposite  the  mid- 
point of  the  normal  pupil.  In  the  center  of  this  spot  is  a  depression  called 
thefovea  centralis  which  is  the  center  of  vision;  only  the  cone-shaped  visual 
cells  are  here  present. 

The  vitreous  body  is  glass-like,  as  its  name  signifies,  both  in 
appearance  and  transparency.  It  consists  of  a  jelly-like  substance 
contained  in  a  hyaloid  membrane  within  the  three  coats.  It  trans- 
mits and  directs  the  rays  of  light  to  the  retina;  also  it  aids  in  pre- 
serving the  shape  of  the  eyeball  (Fig.  214). 

The  crystalline  lens  is  situated  immediately  in  front  of  the 
vitreous  body,  in  a  shallow  depression  like  a  cup  on  the  anterior 
surface.  It  is  a  double  convex  lens  with  a  capsule,  both  perfectly 
transparent  so  that  light  may  pass  through,  and  it  is  able  to  converge 
the  rays  of  light  so  that  they  will  fall  correctly  upon  the  retina. 

The  lens  is  behind  the  iris,  the  margin  of  the  pupil  resting 

22 


338  ANATOMY   AND   PHYSIOLOGY 

lightly  upon  it.  It  is  held  in  place  by  delicate  fibers  which  form 
a  suspensory  ligament;  this  is  normally  a  little  tense,  exerting  a 
slight  but  constant  pressure  upon  the  eyeball. 

The  ciliary  muscle  is  in  the  interior  of  the  eyeball,  around  the  junction  of 
the  choroid  and  iris,  thus  lying  a  little  farther  forward  than  the  border  of  the 
lens.  By  its  action  it  draws  the  suspensory  ligament  forward,  releasing  the 
lens  from  pressure;  thus  it  modifies  the  shape  of  the  lens;  by  this  arrange- 
ment the  eye  is  able  to  accommodate  itself  to  the  different  distances  of  sur- 
rounding objects.  This  is  the  process  of  accommodation.  To  "paralyze  the 
accommodation"  is  to  make  the  ciliary  muscle  powerless,  so  that  the  eye 
cannot  try  to  see  near  objects,  as  it  always  does  unconsciously,  in  its  normal 
condition.  Atropin  will  do  this. 

Clinical  notes. — Inflammation  of  the  iris,  or  iritis,  may  cause  adhesions  to 


Macula  ^  "W^^SS       Retinal  vessel  s 


FIG.  216. — THE  RETINA  AS  SEEN  WITH  THE  AID  OF  THE  OPHTHALMOSCOPE. — (Morris.} 

the  lens  unless  the  margin  of  the  pupil  be  drawn  away.  This  is  the  reason  for 
the  use  of  atropin,  which  weakens  the  circular  fibers  while  it  stimulates  the 
straight  ones,  or,  in  other  words,  dilates  the  pupil. 

Cataract  is  a  thickening  of  the  lens  which  makes  it  opaque  and  gives  it  a 
milky  appearance.  The  remedy  is  excision  or  removal  of  the  lens,  after  which 
a  convex  lens  of  glass  in  front  of  the  eye  gives  a  good  degree  of  vision.  A 
cataract  is  in  an  eye,  not  over  it,  and  must  be  taken  out,  not  off. 

Aqueous  humor  and  chambers  of  the  eye. — The  space  be- 
tween the  cornea  and  the  lens  is  partially  divided  by  the  iris  into 
two  portions — the  anterior  and  posterior  chambers  of  the  eye. 
They  contain  a  thin  clear  fluid,  called  the  aqueous  humor,  which 
floats  the  iris  and  aids  in  preserving  the  shape  of  the  cornea 
(Fig.  214). 

Note. — The  rays  of  light  which  fall  upon  the  retina  must  first 
pass  through  the  media  (or  structures  which  direct  their  course)  in 
the  following  order:  the  cornea,  aqueous  humor,  crystalline  lens,  and 


MYOPIA,    HYPEROPIA  339 

vitreous  body.  Should  any  one  of  these  media  lose  its  transparency, 
vision  would  be  impaired  or  perhaps  lost. 

The  correct  retinal  image  is  the  object  for  which  these  struc- 
tures are  designed.  In  order  that  this  may  be  formed,  the  rays  of 
light  which  are  reflected  from  a  wide  area  of  surrounding  objects 
must  be  made  to  converge  and  meet  on  the  retina,  from  which 
the  stimulus  thus  received  is  conveyed  to  the  brain  by  the  optic 
nerve.  Rays  of  reflected  light  go  toward  the  eye  from  every 
direction  and  by  concentrating  those  which  enter  the  pupil  upon 
the  retina,  a  small  inverted  image  is  formed  which  is  recognized 
by  the  brain  as  representing  the  objects  so  pictured  in  their  proper 
size  and  position. 

This  concentration  of  rays  of  light  is  accomplished  by  the 
refractive  (or  bending)  media  of  the  eye:  the  cornea,  aqueous  humor, 


FIG.  217. — MYOPIA.  FIG.  218 — CORRECTION  or  MYOPIA  BY 

Parallel  rays  focus  at  F,  cross  and  A  CONCAVE  LENS. — (Brubaker.) 

form  diffusion-circles;  divergent  rays 
from  A  focus  on  the  retina. — (Bru- 
baker.) 

crystalline  lens  and  vitreous  body,  in  order.  Each  medium  refracts 
(or  bends)  the  rays  more  and  more  toward  a  common  center  or 
focus.  The  denser  the  media  or  the  more  convex  the  surface, 
through  which  the  light  rays  pass,  the  greater  the  change  in  their 
direction  (the  shorter  the  focus). 

In  the  normal  or  emmetropic  eye  the  focus  is  at  the  retina  and 
a  clear  image  is  formed.  In  the  myopic  or  "near-sighted"  eye  it 
falls  in  front  of  the  retina,  either  because  some  surface  (cornea  or 
lens  or  both)  is  too  convex  or  the  eye  is  too  long,  and  the  rays  of 
light  from  all  except  near  objects,  converge  in  front  of  the  retina. 
The  remedy  is  a  concave  lens  of  glass  to  counterbalance  the 
excessive  convexity  or  length.  (See  Figs.  217  and  218.) 

In  the  hyperopic  or  "far-sighted"  eye,  the  focus  would  fall 
behind  the  retina;  the  surface  of  the  cornea  or  lens  is  not  convex 
enough  or  else  the  eye  is  too  short.  The  rays  of  light  are  not 
sufficiently  bent  to  meet  upon  the  retina  and  the  remedy  is  a 


34O  ANATOMY  AND   PHYSIOLOGY 

convex  lens  of  glass  to  provide  for  the  lack  of  convexity.  (See 
Figs.  219  and  220.) 

In  the  condition  known  as  astigmatism,  the  surfaces  are  ir- 
regularly curved  and  they  form  a  distorted  image;  the  attempt  to 
correct  this  requires  a  constant  effort  which  is  very  injurious  to 
the  eye.  The  remedy  is  a  lens  of  glass  with  counter-balancing 
irregularities. 

Emmetropia  is  the  condition  of  the  normal  eye. 

Myopia  is  near-sightedness. 

Hyperopia  is  far-sightedness.     (This  is  congenital.) 

Astigmatism  may  be  described  as  crooked-sigh tedness. 

Presbyopia  is  the  far-sightedness  of  age  (an  acquired  condition), 
the  tissues  of  the  eyeball  having  lost  their  flexibility  and  resilience. 

The  perception  of  color,  or  color  vision,  has  not  been  quite 


FIG.  219. — HYPERMETROPIA.    PAR-  FIG.  220. — CORRECTION  OF  HYPER- 

ALLEL    RAYS    FOCUSED    BEHIND    THE  METROPIA  BY     A    CONVEX   LENS. — 

RETINA. — (Brubaker.)  (Brubaker.) 

clearly  explained;  consequently,  we  cannot  state  definitely  the 
cause  of  defective  color  vision,  or  color  blindness.  This  is  not 
blindness  to  all  colors,  but  usually  to  red  or  green. 

It  is  supposed  that  certain  different  chemic  substances  in  the  retina  are 
peculiarly  sensitive  to  ether  vibrations  of  different  degrees  of  rapidity, 
whereby  impulses  of  a  corresponding  nature  awaken  in  the  brain  the  sensa- 
tion of  the  various  colors.  In  color  blindness  it  is  not  difficult  to  imagine 
that  some  of  these  sensitive  chemic  substances  may  be  absent,  thereby 
making  it  impossible  for  the  eye  to  perceive  the  corresponding  color  stimulus. 

Range  of  accommodation. — By  this  is  meant  the  distance 
from  the  nearest  to  the  farthest  point  at  which  an  object  can  be 
seen  clearly.  One  can  experiment  for  one's  self  with  any  small 
object,  as  for  example,  with  a  pencil.  By  holding  it  very  near 
to  the  eye  and  gradually  moving  it  away,  the  point  will  be  found 
where  the  image  of  the  pencil  is  clear;  this  is  the  near  point  of 
accommodation  (punctum  proximum  oj  vision).  Moving  it  still 


REFRACTING   MEDIA   OF   EYE  341 

farther  away,  a  point  will  be  found  where  it  can  no  longer  be  seen 
clearly.  This  is  the  far  point  (punctum  remotum).  The  distance 
between  these  points  is  the  measure  of  the  range  of  accommodation. 

RESUME. 

The  sclera  is  protective;  the  cornea  is  protective  and  refractive. 
The  aqueous  humor  preserves  the  shape  of  the  cornea  and  flexibility 
of  the  iris  and  also  refracts  rays  of  light.  The  iris  regulates  the 
amount  of  light  admitted,  contracting  in  strong  light  and  when 
viewing  near  objects.  It  is  relaxed  and  inactive  in  the  absence 
of  light.  (An  active  dilatation  is  caused  in  certain  conditions 
through  stimulation  of  the  radiating  fibers.) 

The  crystalline  lens  refracts  the  rays  of  light  which  enter  the 
eye. 

The  ciliary  muscle,  by  drawing  the  suspensory  ligament  for  ward, 
releases  the  lens  from  pressure,  so  that  it  becomes  more  convex 
and  accommodates  light-rays  from  near  objects.  (Ordinarily, 
the  lens,  prevented  by  the  ligament  from  assuming  its  greatest 
convexity,  is  in  the  position  to  transmit  light  from  more  distant 
objects  to  the  retina.) 

The  vitreous  body  preserves  the  shape  of  the  globe  and  is  also 
refractive. 

The  choroid  and  iris  (meal  tract)  constitute  the  dark  chamber  of 
the  eye. 

The  retina  is  the  sensitive  nerve  layer. 

APPENDAGES  OF  THE  EYE 

The  eyebrows,  resting  upon  the  superciliary  ridges,  or  eleva- 
tions caused  by  the  frontal  sinuses  (p.  21),  serve  to  extend  the 
protection  given  by  the  orbit. 

The  eyelids  (or  palpebrae,)  attached  to  the  margin  of  the  orbits 
are  necessary  for  the  protection  of  the  eye.  They  have  five  layers, 
—skin,  smooth  and  thin;  fascia — thin  and  delicate;  muscle — the 
palpebral  portion  of  the  orbicular  muscle;  fibrous — containing  a 
stiff  plate  of  connective  tissue,  the  tarsal  plate;  and  mucous — the 
layer  which  lines  the  lid  (conjunctiva). 

The  conjunctiva  (or  conjunctival  sac)  is  the  sensitive  mucous 
membrane  which  is  attached  to  the  margins  of  the  lids  to  line  them 


342 


ANATOMY  AND  PHYSIOLOGY 


and  to  cover  the  front  of  the  eyeball.  The  portion  which  lines 
the  lids  is  the  palpebral  conjunctiva,  that  which  covers  the  ball 
is  the  bulbar  or  ocular  conjunctiva. 

The  tar  sal  glands  are  in  the  tarsal  plates;  their  oily  secretion 


Superior  lacrimal   gland 
Inferior  lacrimal  gland 


Ducts  from  superior 
gland 


Upper  eyelid  partly 
divested  of  skin 


Upper  punctum 

Lacrimal  sac,  near  its 
fundus 

Common  duct,  formed 
by  junction  of  upper 
and  lower  ducts 

Lower  punctum 


Naso-lacrimal  duct 


FIG.  221. — LACRIMAL  APPARATUS. — (Morris.) 

prevents  the  lids  from  adhering  to  each  other.     (They  are  called 
Meibomian  glands.} 

The  angles  formed  by  the  extremities  of  the  eyelids  are  the 
medial  and  the  lateral  angles  (inner  and  outer  canthi).  At  the 
medial  angle,  each  lid  presents  a  small  elevation,  the  lacrimal 


FIG.  222. — THE  MUSCLES  OF  THE  EYEBALL. — (Holden.)    \ 
A  small  section  of  the  upper  eyelid  is  shown. 

papilla,  with  a  minute  opening  (punctum)  where  the  tears  enter  a 
small  canal  which  leads  to  the  lacrimal  sac;  from  the  lacrimal  sac 
they  flow  through  the  nasal  duct  to  the  nasal  cavity. 

The  eyelashes,  or  cilia,  are  kept  soft  and  flexible  by  an  oily 


THE   LACRIMAL   GLAND  343 

substance  secreted  by  their  own  oil  glands  in  the  margin  of  the 
lids.  The  cilia  of  the  upper  lid  curve  upward,  those  of  the  lower 
lid  curve  downward;  they  never  interlace.  They  guard  the  eye 
from  foreign  bodies — as  coal  dust,  etc.,  floating  in  the  surrounding 
air. 

The  space  between  the  margins  of  the  eyelids  is  called  the 
inter p alp ebral  slit  (palpebral  fissure).  It  varies  with  the  action 
of  the  lids;  the  opening  and  closing  of  the  slit  is  done  by  the 
upper  lid  mainly,  the  lower  one  moving  but  very  little.  (Muscles 
— orbicularis  closes,  levator  palpebrce  opens .  (See  p.  89.) 

Lacrimal  gland. — The  gland  which  secretes  the  tears.  It  is 
situated  in  the  lacrimal  fossa  of  the  frontal  bone,  beneath  the 
lateral  end  of  the  orbital  arch,  and  has  several  ducts  for  the  dis- 
charge of  the  tears  under  the  upper  eyelid.  The  tears  flow  across 
the  eyeball  and  bathe  the  conjunctiva,  washing  away  the  dust  and 
other  fine  particles  of  foreign  substances,  which  would  be  injurious 
if  allowed  to  attach  themselves  to  the  conjunctiva.  They  are  con- 
ducted by  tiny  canals  (canaliculi)  into  the  lacrimal  sac  and  nasa> 
duct  (see  Fig.  221)  thence  to  the  nasal  fossa.  Being  a  thin  saline 
solution  they  are  unirritating  to  mucous  membranes. 

Clinical  note. — The  conjunctiva  is  supplied  with  blood-vessels 
most  of  which  are  invisible  except  when  they  become  congested. 
In  active  inflammation  or  conjunctivitis  they  are  so  enlarged  as  to 
give  the  membrane  a  bright  red  color. 

Motions  of  the  eyeball. — The  eyeball  is  moved  by  six  slender 
muscles,  which  have  their  origin  at  the  apex  of  the  orbit  and  their 
insertion  upon  the  sclera  at  a  little  distance  from  the  cornea. 
These  are  the  orbital  muscles. 

The  superior  rectus  rolls  the  ball  upward.     (Third  nerve.) 
The  inferior  rectus  rolls  the  ball  downward.     (Third  nerve.) 
The  internal  rectus  rolls  the  ball  inward.     (Third  nerve.) 
The  external  rectus  rolls  the  ball  outward.     (Sixth  nerve.) 
The  superior  oblique  rolls  the  ball  downward  and  outward. 
(Fourth  nerve.) 

The  inferior  oblique  rolls  the  ball  upward  and  outward.  (Third 
nerve.) 

Clinical  note. — If  these  muscles  are  well  balanced  the  pupil  is 
directed  straight  forward  while  they  are  at  rest,  but  if  they  are  of  quite 
unequal  strength  the  eye  will  be  turned  habitually  in  some  special 


344 


ANATOMY   AND   PHYSIOLOGY 


direction.     This  condition  is  called  squint  or  strabismus,  or  "cross-eye." 
It  oftenest  happens  with  either  the  internal  or  external  rectus. 

The  muscles  of  the  iris  and  the  ciliary  body  are   the  ocular 
muscles. 

Associated  movements  are  of  interest  in  connection  with  the 
eye.  The  central  connections  are  so  arranged  that  the  external 
rectus  of  one  eye  moves  with  the  internal  rectus  of  the  other; 
the  internal  recti  of  the  two  eyes  act  together  when  they  are 
directed  toward  a  near  object.  The  act  of  convergence  is  asso- 
ciated with  contraction  of  the  pupil  and  ac- 
commodation. It  is  easily  understood  that 
fixing  the  eye  upon  a  near  object  is  not  a 
simple  act : — the  circular  fibers  of  the  iris, 
the  ciliary  muscle  and  the  internal  recti  are 
all  called  into  action.  (The  far-sighted  eye 
is  doing  this  work  constantly;  it  is  there- 
fore important  to  relieve  this  strain  of 
overwork  by  well-fitted  lenses.) 


FIG.  223. — INTERIOR  OF 
LARYNX  (LEFT  SIDE  RE- 
MOVED).— (Sappey.) 

2,  Epiglottis;  5,  so-called 
"false  vocal  cord";  9,  vocal 
band;  13,  thyroid  cartilage; 
14,  arytenoid  cartilage. 


text. 


THE  VOICE 

The  voice,  by  which  we  establish  most 
frequent  communication  with  the  outside 
world,  is  a  special  endowment  for  the  ex- 
pression of  ideas  awakened  in  conscious- 
ness by  the  senses.  It  is  therefore  not 
inappropriately  considered  in  this  con- 
nection. 

The  larynx  is  the  organ  of  the  voice. 

(The  larynx,  lips,  tongue  and  teeth  are  the  organs  of  speech.) 
A  brief  description  of  the  larynx  is  given  on  page  234,  of  tongue 
and  teeth,  pp.  132,  35. 

The  structures  which  are  specially  concerned  in  the  production 
of  the  voice,  in  addition  to  the  cartilages  described,  are  the 
vocal  bands  (also  known  as  vocal  cords,  and  true  weal  cords). 
These  are  stretched  across  the  larynx  from  front  to  back,  being 
attached  to  the  thyroid  cartilage  anteriorly  and  the  two  arytenoid 
cartilages  posteriorly,  thus  dividing  the  cavity  into  upper  and  lower 
portions  (Fig.  223). 


ORGANS   OF   SPEECH  345 

The  arytenoid  cartilages  are  shaped  like  a  triangular  pyramid 
with  a  curved  apex.  They  rest  upon  the  cricoid  cartilage  and  form 
with  it  movable  joints  having  ligaments  and  synovial  membranes. 
These  are  gliding  joints.  They  allow  the  rotation  of  the  arytenoids 
upon  the  articular  facets  of  the  cricoid. 

The  vocal  bands  are  composed  of  fibrous  and  muscle  tissue 
covered  with  mucous  membrane.  The  space  between  them  is 
the  glottis. 

Small  muscles,  belonging  altogether  to  the  larynx,  control  the 
position  and  tension  oj  the  weal  bands  by  their  action  on  the 
arytenoid  cartilages  to  which  the  bands  are  attached,  thus 
producing  the  different  tones  of  the  voice  as  the  breath  passes 
between  them.  Tense  bands  and  a  narrow  glottis  are  necessary  for 
a  high  note.  Lax  bands  and  a  wide  glottis  are  the  conditions  for  a 
low  note. 

Above  them  are  two  membranous  folds,  one  on  either  side, 
formerly  called  false  weal  cords. 

Note. — It  has  been  generally  taught  that  the  voice  is  caused  by  vibrations 
of  the  vocal  bands,  but  accurate  observations  by  Miss  Alice  Groff,  of  Phila- 
delphia, and  other  investigators,  have  proved  that  this  is  not  the  case,  the 
voice-sounds  being  like  those  of  a  horn  rather  than  a  stringed  instrument. 

With  the  aid  of  lips,  tongue,  and  teeth,  the  voice  sounds  are  so 
modified  that  speech  becomes  possible,  and  with  it  the  expression 
of  ideas,  and  communication  between  individuals. 

The  various  air  sinuses  which  communicate  with  the  nasal 
fossae  act  as  resonance  chambers.  They  give  to  the  voice  an  agree- 
able quality  of  tone,  which  is  in  marked  contrast  to  the  sound 
produced  when  the  air  current  cannot  enter  these  chambers,  as  in 
coryza  (when  the  mucous  membrane  is  so  swollen  as  to  prevent  free 
admission,  to  the  sinuses,  thus  causing  the  nasal  tone) . 


CHAPTER  XXV 
THE  PELVIC  ORGANS 

IN  THE  MALE  PELVIS.  IN  THE  FEMALE  PELVIS. 

The  rectum.  The  rectum. 

The  urinary  bladder.  The  urinary  bladder. 

The  prostate  gland.  The  uterus. 

The  ovaries,  and  uterine  tubes. 

The  vagina. 

The  Rectum  is  already  described  (page  146). 

The  Bladder  is  the  receptacle  and  reservoir  for  the  urine  and  is 
situated  in  the  pelvis  just  behind  the  pubic  bones. 

It  is  described  with  the  urinary  organs  (p.  246). 

In  the  male  pelvis  the  bladder  is  in  front  of  the  rectum  and  in 
contact  with  it  for  a  short  distance  in  the  lower  part.  Above  this 
point  the  peritoneum  dips  between  the  two  organs  forming  the 
recto-vesical  pouch  (p.  352,  Fig.  227). 

The  prostate  gland  is  situated  at  the  base  of  the  bladder,  im- 
mediately in  front  of  the  rectum  and  surrounding  the  first  portion 
of  the  urethra. 

In  the  female  pelvis  the  relations  of  the  bladder  are  different. 
The  base  is  immediately  in  front  of  the  lower  portion  of  the  uterus 
and  upper  portion  of  the  vagina,  the  urethra  lying  close  to  the 
vaginal  wall.  The  peritoneum  which  dips  between  the  bladder 
and  uterus  forms  the  utero-vesical  pouch. 

v-X  " 

THE  UTERUS  AND  APPENDAGES 

These  constitute  the  internal  generative  organs. 
The  appendages  are  the  uterine  (or  Fallopian)  tubes  and  the 
ovaries. 

THE  UTERUS 

The  uterus,  or  womb,  is  situated  between  the  bladder  and  the 
upper  part  of  the  rectum.  It  is  a  hollow  organ  shaped  somewhat 
like  a  pear,  about  two  and  one-half  or  three  inches  long,  and  one 

346 


STRUCTURE   OF   THE   UTERUS 


347 


and  one-half  inches  wide  at  the  larger  end,  which  is  called  the 
fundus  and  is  placed  uppermost. 

The  uterus  is  composed  of  non-striated  muscles,  arranged  in 
three  layers  and  lined  with  mucous  membrane  bearing  ciliated 
epithelium.  Its  walls  are  about  three-eighths  of  an  inch  thick. 
It  consists  of  two  portions,  the  body  and  the  neck  or  cervix,  the 
body  being  a  little  longer  of  the  two. 

POSTERIOR  SURFACE  OF  BODY  OF  UTERUS 
I 

TTtero-ovarian  ligament 
OVARY 

FALLOPIAN  TUBE 

Broad  ligament 


Inf  undlbul  urn 
FJmbria 
Broad  ligament 


Vaginal  walls 


FIG.  224. — UTERUS  AND  APPENDAGES,  POSTERIOR. — (Morris.} 

The  body  is  flattened,  but  is  more  convex  at  the  back  than  in 
front;  the  cervix  is  round. 

The  cavity  of  the  uterus  corresponds  to  the  general  shape  of  the 
organ,  being  triangular  in  the  body  and  round  in  the  cervix.  At 
the  upper  angles  of  the  body  are  the  openings  which  lead  into  the 
uterine  or  Fallopian  tubes.  Between  the  body  and  the  cervix  is 
the  internal  os,  the  opening  at  the  lower  extremity  of  the  cervix 
being  called  the  external  os,  which  is  bordered  by  the  anterior 
and  posterior  lips.  The  uterus  is  covered  with  peritoneum,  except 
in  front  of  the  cervix. 


348 


ANATOMY   AND   PHYSIOLOGY 


When  the  uterus  receives  an  impregnated  ovum  its  function  is 
exercised  in  protecting  and  nourishing  the  growing  embryo  until 
it  becomes  a  fully  developed  fetus.  The  mucous  membrane 
thickens  to  form  a  bed  for  the  embryo,  and  becomes  a  part  of  the 
placenta  or  "  afterbirth."  The  muscle  fibers  grow  in  size  and 

number  and  the  weight 
increases  from  the  origi- 
nal ounce  and  a  half  to 
one  or  more  pounds. 

The  function  of  the 
uterus  is  concluded  with 
the  expulsion  of  the 
fetus  and  placenta.  It 
then  contracts  rapidly, 
and  the  process  of  invo- 
lution softens  and  dis- 
charges the  remains  of 
tissue  which  is  no  longer 

FIG.  225.— THE  UTERUS.  needed.      (See    p.     358, 

Showing  cavity  and  attachment  of  vagina. —  7     7  •    \ 

Morris.}  lochta.) 

Position. — Thefundus  of  the  uterus  is  normally  inclined  somewhat  forward,  while 
the  os  externum  looks  downward  and  backward.  If  the  fundus  turns  too  far 
forward  this  is  anteversion;  if  it  inclines  backward,  retr aversion. 

A  bend  may  exist  where  the  neck  joins  the  body.  This  is  flexion.  When  the 
body  is  bent  forward,  this  is  anteflexion;  when  backward,  retroflexion. 

THE  UTERINE  TUBES  (FALLOPIAN  TUBES) 

The  uterine  tubes  (Fallopian  tubes)  two  in  number  (Fig.  224), 
extend  outward  from  the  upper  angles  of  the  uterus;  they  have  a 
fibre-muscular  structure  and  are  lined  with  mucous  membrane. 
Each  tube  is  about  four  inches  long.  At  the  beginning  it  is  only 
large  enough  to  allow  the  passage  of  a  small  bristle,  but  it  becomes 
larger  toward  the  end,  expanding  into  a  trumpet-shaped  extremity 
called  the  infundibulum,  which  is  fringed  or  fimbriated,  and  which 
is  connected  with  the  ovary  below  by  a  slender  band  (or  fimbria). 

The  function  of  the  uterine  tube  is  to  convey  the  ovum  from 
the  ovary  to  the  cavity  of  the  uterus. 

THE  OVARIES 

The  ovaries,  two  in  number,  lie  on  either  side  of  the  body  of 
the  uterus,  each  one  being  connected  to  it  by  a  short  cord  called 


OVULATION  349 

the  ovarian  ligament.  An  ovary  is  about  three-quarters  of  an 
inch  long,  a  half-inch  wide,  and  shaped  like  an  almond  (Figs. 
224,  226). 

The  ovaries  are  covered  with  peritoneum  (except  at  the  border 
where  vessels  enter  and  leave). 

Structure  of  the  ovary. — A  collection  of  connective- tissue 
fibers  enclosing  many  vessels  and  nerves,  and  a  multitude  of  little 
ovisacs  (egg  sacs)  called  Graafian  follicles.  These  follicles  are 
at  first  microscopic  in  size,  but  when  developed  they  may  be  seen 
by  the  naked  eye.  Each  one  contains  an  ovum,  or  egg. 

Ovulation. — As  the  follicle 
with  its  ovum  grows  in  size  it 
approaches  the  surface  of  the 
ovary,  and  when  it  is  mature 
the  sac  ruptures  and  the  ovum 
escapes,  to  be  taken  by  the  uter- 
ine tube  to  the  uterus,  from 
which  it  is  discharged  through 

the  vagina,  usually  with  a  quan-          FIG.    226. — OVARY    WITH  MATURE 
r  11      j  GRAAFIAN  FOLLICLE  ABOUT   READY  TO 

:ity  c  RuRST.—(Ribomont-Dessaignes-Lewis.) 

The  function  of   the  ovary 

(ovulation)  begins  with  puberty,  which  is  the  maturing  of  the 
pelvic  organs  and  mammary  glands.  It  is  usually  established  at 
about  fourteen  years  of  age  (earlier  in  warm  climates,  later  in 
cold).  From  that  time  the  development  of  at  least  one  ovum 
occurs  in  (about)  every  twenty-eight  days  until  the  menopause  is 
established. 

Menstruation  is  the  periodical  discharge  of  blood  from  the 
uterus.  The  mucous  membrane  thickens  and  sheds  its  superficial 
cells,  which  are  renewed  after  the  flow  ceases.  This  probably 
accompanies  ovulation.  When  an  impregnated  ovum  reaches  the 
uterus  menstruation  is  suspended. 

The  cessation  of  menstruation  is  the  menopause  or  climacteric. 
It  often  occurs  at  about  forty-five  years  of  age  and  may  be  as 
late  as  fifty  or  over.  It  is  followed  by  gradual  atrophy  of  the 
generative  organs. 

Corpus  luteum  is  the  name  given  to  a  yellow  substance  which  forms  in  the 
ruptured  Graafian  follicle.  It  ordinarily  shrinks  and  disappears  within  a 
month.  Immediately  after  the  rupture  the  follicle  fills  with  blood;  this 
forms  the  corpus  hemorrhagicum,  changes  to  the  corpus  luteum  and  this  in 


350  ANATOMY  AND   PHYSIOLOGY 

turn  is  succeeded  by  a  whitish  spot  called  the  corpus  albicans.  If  conception 
has  taken  place,  the  corpus  albicans  is  not  formed.  The  corpus  luteum 
persists,  grows  larger  and  remains  present  until  the  end  of  pregnancy. 

The  ovary  has  been  included  in  the  list  of  ductless  glands. 
Its  internal  secretion  is  not  discovered,  but  there  is  undoubted 
clinical  evidence  that  the  corpus  luteum  contains  at  least  one 
autocoid  substance,  .since  many  of  the  sequelae  which  follow  the 
removal  of  the  ovaries  are  prevented  by  the  use  of  extract  of 
corpus  luteum  (or  lutein).  By  this  means  the  system  is  supplied 
with  something  of  which  it  had  been  deprived.  (The  medicinal 
extracts  are  made  from  the  ovaries  of  swine.) 

THE  VAGINA 

The  Vagina  is  the  muscular  canal  extending  from  the  uterus  to 
the  surface  of  the  body,  where  it  terminates  at  the  vaginal  orifice 
(Figs.  165,  224). 

It  is  situated  between  the  base  of  the  bladder  in  front  and  the 
lower  portion  of  the  rectum  behind,  from  which  organs  it  is 
separated  by  connective  tissue  septa  (vesico-vaginal,  and  recto- 
vaginal  septa).  It  curves  slightly  forward,  is  four  inches  long  in 
its  posterior  wall  and  about  two  and  three-quarter  inches  in  the 
anterior.  It  has  two  layers  of  muscles,  strengthened  by  fibrous 
tissue  and  lined  by  mucous  membrane  which  lies  in  transverse 
folds.  The  columns  of  the  vagina  are  two  median  ridges,  one  on 
the  anterior  and  one  on  the  posterior  wall,  extending  throughout 
their  length. 

The  vagina  is  attached  to  the  cervix  of  the  uterus  at  a  little 
distance  above  the  external  os  (about  half  an  inch  in  front  and 
three-quarters  of  an  inch  at  the  back);  therefore  the  examining 
finger  may  feel  the  cervix  projecting  into  the  canal.  This  is  the 
infra-vaginal  portion  of  the  cervix  (Fig.  224,  227).  The  portion 
of  the  vagina  which  is  attached  to  the  cervix  is  thefornix  (or  roof) . 

Note. — The  urethra  lies  close  to  the  anterior  vaginal  wall,  feeling  like  a 
thick  cord  in  the  septum  between  the  two  canals  (the  urethro-vaginal  septum). 

LIGAMENTS  OF  THE  UTERUS 

The  uterus  is  sustained  in  the  pelvis  by  folds  of  peritoneum 
which  connect  it  to  the  pelvic  walls  and  to  the  bladder  and 
rectum.  The  principal  ones  are  the  broad  ligaments  (Fig.  224). 


LIGAMENTS    OF    THE    UTERUS  351 

The  broad  ligaments  are  folds  of  peritoneum  extending  laterally 
from  the  sides  of  the  uterus,  like  wings,  to  the  sides  of  the  pelvic 
cavity.  Each  fold  encloses  the  uterine  tube,  ovary,  and  round 
ligament  of  its  own  side. 

The  round  ligaments  are  two  muscular  and  fibrous  cords, 
which  extend  from  the  angle  of  the  uterus  lateralward  and  for- 
ward through  the  inguinal  canal,  to  be  attached  to  the  tissues  upon 
the  pubic  bone.  They  aid  in  preserving  the  normal  position  of 
the  uterus  with  the  fundus  forward.  This  position  is  still  further 
secured  by  utero-sacral  ligaments,  which  connect  the  junction  of 
the  cervix  and  body  of  the  uterus  with  the  second  and  third 
pieces  of  the  sacrum,  thus  holding  the  cervix  back.  (They  pass 
one  on  either  side  of  the  rectum.) 

THE  EXTERNAL  GENERATIVE  ORGANS 

The  pudendum  muliebre  (vulva)  .• — The  name  given  to  the 
parts  situated  in  front  of  the  pubic  arch  of  the  female  pelvis. 
They  are: 

The  mons  veneris,  a  cushion  of  adipose  and  fibrous  tissue  in 
front  of  the  body  of  the  pubic  bone. 

The  labia  majora. — Two  folds  of  skin  containing  adipose  and 
loose  connective  tissue,  continuous  in  front  with  the  mons,  and 
joined  together  posteriorly  by  a  fold  of  skin  called  the  posterior 
commissure,  about  an  inch  in  front  of  the  anus.  (The  depression 
in  front  of  this  commissure  is  the  fossa  navicularis .) 

The  space  between  the  labia  majora  is  the  pudendal  cleft. 

The  labia  minora. — Two  folds  situated  between  the  labia 
majora,  about  one-half  as  long,  and  joined  anteriorly  in  the  hood 
of  the  clitoris.  B  etween  them  is  the  space  called  thevestibule.  (They 
sometimes  unite  posteriorly  in  a  thin  fold  called  the  frenulum.) 

The  clitoris. — A  small  body,  somewhat  less  than  an  inch  in 
length,  nearly  covered  by  the  hood.  It  contains  many  vessels 
and  nerves.  The  extremity  is  called  the  glans  of  the  clitoris;  the 
hood  is  normally  free  from  the  glans  and  if  adhesions  form  they 
should  be  separated,  since  they  are  a  source  of  nervous  irritation. 

The  vestibule. — A  triangular  space  below  the  clitoris,  and 
between  the  labia  minora.  In  the  middle  of  the  vestibule  is  the 
orifice  of  the  urethra,  or  external  meatus. 

Below  the  vestibule  is  the  orifice  of  the  vagina,  or  vaginal  orifice, 


352 


ANATOMY   AND   PHYSIOLOGY 


partially  closed  by  a  circular  fold  of  mucous  membrane  called  the 
hymen. 

The  ragged  edges  left  by  rupture  of  the  hymen  are  called 
carunculcR  myrtiformes.  An  imperforate  hymen  is  one  which 
extends  entirely  across  the  vaginal  orifice,  closing  it  altogether. 
A,  little  way,  laterally,  from  the  middle  of  the  hymen  are  the 
openings  of  the  ducts  of  the  glands  of  Bartholin,  one  on  either 
side  (or  vulvo-vaginal  glands).  Not  infrequently  they  become 
infected  and  swell  rapidly,  forming  an  abscess. 


THE  PERITONEUM  OF  THE  PELVIS 

The  peritoneum  of  the  pelvis  (Fig.  227)  is  a  portion  of  the 
general  peritoneum.  It  lines  the  pelvic  walls,  covers  the  rectum 
(except  the  lowest 'part)  and  other  pelvic  organs,  and  the  floor. 


Liver 

Gastro-hepatic  omentum 

Stomach- 
Transverse  colon 
Mesentery 

Small  intestine 

Uterus  — 

Bladder 


Epiploic  foramen 
Pancreas 

Duodenum 

Transverse  meso-colon 
Aorta 


Rectum 


FIG.  227. — DIAGRAM  or  A  SAGITTAL  SECTION  OF  THE  TRUNK,  SHOWING  THE  RELA- 
TIONS OF  THE  PERITONEUM.     (Allen  Thompson.) 

In   the  male  pelvis  it  dips  between  the  rectum  and  bladder 
forming  the  recto-vesical  pouch. 

In  the  female  pelvis  it  forms  a  utero-vesical  pouch  in  front  of  the 


THE  PERINEUM 


353 


uterus,  and  a  utero-rectal  pouch  behind  it.  It  also  extends  over 
the  tubes,  ovaries,  and  round  ligaments  at  the  sides,  thus  making 
the  folds  called  the  broad  ligaments,  which  connect  the  uterus  with 
the  sides  of  the  pelvic  cavity. 

The  utero-rectal  pouch  is  the  pouch  of  Douglas  (or  Douglas's 
cul-de-sac).  It  is  the  lowest  part  of  the  peritoneal  cavity,  ex- 
tending down  an  inch  or  more  behind  the  vagina. 

Note. — The  pelvis  of  the  infant  (see  Fig.  48),  is  undeveloped 
and  the  pelvic  organs  lie 
partly  in  the  abdomen.  As 
growth  advances  they  are  fi- 
nally contained  in  the  pelvis, 
at  about  the  fourteenth  year. 

Perineum.— The  name 
perineum  properly  signifies 
the  parts  bounded  by  the  out- 
let of  the  pelvis,  but  we  gen- 
erally apply  it  to  the  portion 
in  front  of  the  rectum. 

In  the  female  perineum, 
the  part  between  the  lower 
ends  of  the  vagina  and  rectum 
is  the  perineal  body.  This  is  FlG  228._SHOWING^;TIS 

a    triangular  body   composed      DEFERENS  SUSPENDED  BY  SPERMATIC  CORD. 

r  ....  i.       —(Holden.) 

of  connective  tissue  and  adi- 
pose, the  base  of  the  triangle  being  covered  by  skin  and  measuring 
about  one  inch,  between  the  vulva  and  the  anus.     It  contains 
several  muscles,  some  of  which  are  connected  with  the  sphincter  ani. 

The  perineum  is  distensible,  and  stretches  to  a  remarkable 
extent  during  labor. 

From  the  male  perineum  a  pouch  of  skin  and  fascia  is  suspended, 
called  the  scrotum.  The  fascia  contains  scattered  muscle  fibers 
and  is  called  the  dartos. 

The  scrotum  contains  the  testes  which  are  two  in  number,  the 
right  and  the  left.  They  consist  essentially  of  minute  tubes  in 
which  the  seminal  fluid  is  secreted,  and  which  open  into  larger 
ones  leading  to  the  duct  of  the  testis,  or  the  ductus  defer  ens. 

The  function  of  the  testis  is  the  formation  of  spermatozoa  (or 
s  per  mid)  from  the  cells  which  line  the  tubes. 
23 


354  ANATOMY  AND  PHYSIOLOGY 

The  spermatozoon  is  the  male  germinal  cell  (often  called  the 
sperm  celt).  It  is  carried  by  the  seminal  fluid  through  the  ductus 
defer  ens  to  the  urethra  from  which  the  fluid  is  discharged. 

The  ductus  deferens  passes  upward  from  the  testis  through  the 
subcutaneous  ring  and  the  inguinal  canal,  then  down  into  the 
pelvis  and  beneath  the  bladder,  where  it  runs  forward  to  enter  the 
urethra. 

The  spermatic  cord. — The  testis  is  suspended  in  the  scrotum 
by  the  spermatic  cord,  which  reaches  from  the  abdominal  inguinal 
ring  to  the  bottom  of  the  scrotum,  and  contains  the  cremaster 
muscle.  Contraction  of  the  cremaster  muscle  lifts  the  testis  and 
draws  it  upward  in  the  scrotum  (Fig.  228). 

Descent  of  the  Testis. — During  fetal  life  the  testis  is  situated  in 
the  abdominal  cavity,  just  below  the  kidney,  but  it  slowly  descends 
to  pass  through  the  inguinal  canal,  reaching  the  subcutaneous  ring 
at  about  the  eighth  month,  and  at  birth  it  should  be  in  the  scrotum. 
It  may  descend  more  slowly,  or  may  be  arrested  at  any  point,  but 
usually  finds  its  place  in  time. 

In  the  scrotum  it  is  surrounded  by  a  double  sheath  of  the  peritoneum 
(tunica  -vaginalis)  which  accompanied  it,  and  which  became  shut  off  from  the 
great  peritoneal  sac  as  the  subcutaneous  ring  closed  around  it.  It  is  a  serous 
sac,  having  visceral  and  parietal  layers. 

In  caring  for  the  male  infant  it  is  important  to  note  the  condition  of  the 
foreskin  (or  prepuce).  This  is  a  fold  of  skin  which  covers  the  glans  penis.  It 
should  be  sufficiently  loose  to  be  easily  drawn  back,  or  retracted,  in  order  that 
careful  cleansing  of  the  parts  may  prevent  accumulations  of  sebaceous  mate- 
rial, or  smegma.  If  this  is  not  done,  irritation  is  caused  by  retained  substances 
and  also  by  adhesions  which  are  apt  to  form. 

Circumcision  is  cutting  off  the  foreskin  (literally — cutting  around}. 

Hydrocele  is  a  collection  of  serous  fluid  in  the  vaginal  tunic  of  the  testis. 

Impregnation. — The  entrance  of  the  spermatozoon  into  the 
ovum  causes  impregnation  or  conception.  The  spermatozoon 
reaches  the  ovum  after  passing  through  the  vagina  and  uterus  into 
the  uterine  tube;  it  is  here  that  conception  usually  occurs,  in  an 
ovum  which  has  entered  the  tube  on  its  way  to  the  uterus.  The 
head  (or  nuclear  part)  of  the  sperm  cell  unites  with  the  nucleus  of 
the  ovum  to  form  one  new  or  "parent  cell."  By  division  of  its 
substance  this  cell  forms  many  new  ones  (all  contained  within 
the  wall  of  the  parent  cell),  each  composed  of  the  united  original 
elements.  A  series  of  rapid  changes  follows  and  a  re- arrangement 


THE  DECIDUA 


355 


of  the  new  cells  into  three  layers,  from  which  the  different  parts 
of  the  body  of  a  new  being  and  the  membranes  which  envelop 
it,  will  develop.  When  the  impregnated  ovum  reaches  the  uterus 
it  finds  extensive  preparations  already  made  for  its  reception. 
Instead  of  being  washed  away  by  menstrual  fluid,  it  is  deposited 
in  a  soft  bed  of  the  thickened  mucous  lining  of  the  uterus  which 
has  developed  an  increased  growth  and  new  features  for  the 
purpose.  As  this  membrane  will  be  discarded  after  the  birth  of 
the  child,  it  is  called  a  true  decidua,  or  decidua  vera  (Fig.  229.) 

The  impregnated  ovum  becomes   attached   to  the  mucous 
membrane  usually  near  the  fundus  (see  Fig.  230).     This  area  of 


FIG.  229. — THICK- 
ENED LINING  OF  A 
PREGNANT  UTERUS. 

Showing  decidua 
vera,  decidua  serotina 
and  beginning  of  the 
reflexa. — (Dalton.) 


FIG.  230.— THICKENED 
LINING  OF  A  PREGNANT 
UTERUS. 

Showing    decidua    reflexa. 
— (Dalton.) 


fixation  becomes  the  decidua  serotina.  A  portion  of  the  decidua 
vera  rises  on  every  side  of  the  ovum  and  thus  forms  a  third  decidua, 
the  decidua  reflexa  which  finally  encloses  it.  As  the  ovum  grows 
and  the  fetus  develops  to  fill  the  uterine  cavity,  the  decidua  reflexa 
becomes  fused  with  the  decidua  vera  and  together  they  are  dis- 
charged in  the  lochia.  The  serotina  becomes  a  part  of  the  placenta. 


The  decidua  vera  is  the  uterine  decidua. 

The  decidua  reflexa  is  the  ovular  decidua.     (Together  these  two 
disappear  in  the  lochia.) 

The  decidua  serotina  is  the  placental  decidua. 


356 


ANATOMY  AND   PHYSIOLOGY 


Right  innominate  vein 

Superior  vena  cava 
Right  pulminary  artery 


Inferior  vena  ca 


Left  branch  of  portal  vein 
Ductus  venosus 


Umbilical  vein 
Portal  vein 

Right  branch  of 
portal  vein 


Umbilical  vein 
Umbilical  arteries 

Umbilical  artery 


Left  innominate 
vein 

Arch  of  aorta 
Ductus  arteriosus 
Left  pulmonary 
artery 


Descending  aorta 


Superior 
esenteric  artery 


Splenic  vein 

Superior 
mesenteric  vein 


Inferior 
mesenteric  artery 


Left  common  iliac 
artery 


Hypogastric  artery 

External  iliac 
artery 


FIG.  231. — THE  HEART,   WITH  THE  ARCH   OF  THE  AORTA,  THE  PULMONARY  ARTERY,  THE 
DUCTUS  ARTERIOSUS,  AND  THE  VESSELS  CONCERNED  IN  THE  FETAL  CIRCULATION.— (Morris.) 
(From  a  preparation  of  a  fetus  in  the  Museum  of  St.  Bartholomew's  Hospital. 


THE   PLACENTA  357 

The  fetus  is  enclosed  in  the  amniotic  sac  which  is  formed  by  the  fusion 
of  two  membranes  (amnion  and  chorion)  derived  from  layers  of  the  original 
cell.  It  is  often  called  "the  membranes." 

It  contains  amniotic  fluid — a  clear  saline  solution  in  which  the  fetus 
floats.  The  placenta  is  developed  in  the  outer  layer  of  the  sac  (chorion). 

Clinical  note. — It  is  sometimes  possible  to  separate  the  two  layers  of  mem- 
brane to  a  partial  extent. 

The  placenta  is  a  mass  of  uterine  and  fetal  blood  and  lymph 
vessels,  held  loosely  together.  The  vessels  of  the  decidua  serotina 
are  branches  of  the  uterine  arteries,  which  form  thinly  covered 
loops  called  mill.  These  are  received  between  similar  villi  of  the 
fetal  vessels,  forming  the  placenta.  The  blood  of  these  two  sets  of 
vessels  is  separated  only  by  the  thinnest  of  membranes,  so  that 
the  respiration  (or  exchange  of  O  and  COz)  of  the  infant  is  thus 
provided  for,1  the  impure  blood  arriving  from  the  fetus  by  two 
arteries  (right  and  left  hypogastric)  and  returning  purified  to  the 
fetus  by  one  vein,  the  umbilical  (Fig.  231). 

Point  of  interest. — The  function  of  these  vessels  is  similar  to  that  in  the 
lungs  of  extra-uterine  life,  where  the  right  and  left  pulmonary  arteries  carry 
impure  blood  to  the  lungs  and  pulmonary  veins  carry  pure  blood  to  the  heart. 

Note. — The  placenta  is  not  within  the  amniotic  sac.  The  fetal  surface  is 
smooth,  a  part  of  the  sac  itself;  the  maternal  or  uterine  surface  is  irregular, 
dark  red  and  friable  (easily  separated  into  its  original  masses  of  vessels  and 
connective  tissue  called  cotyledons). 

Pregnancy  or  gestation  is  the  condition  in  which  these  proc- 
esses are  going  on.  It  begins  with  conception  and  ends  with  the 
expulsion  of  the  fully  developed  fetus  from  the  uterus,  or 
parturition. 

The  normal  duration  of  pregnancy  is  280  days  or  ten  lunar 
months.  During  the  first  five  months  the  growth  is  very  rapid; 
the  length  of  the  fetus  increases  from  one  centimeter  in  the  first 
month  to  twenty-five  in  the  fifth  (about  10  inches).  After  the 
fifth  month  the  growth  advances  steadily  but  not  so  rapidly. 
The  average  length  at  birth  is  about  fifty  centimeters,  and  the 
average  weight  2737  grams,  or  7  1/3  Ibs. 

The  growth  of  the  uterus  to  accommodate  the  growing  fetus 

has  been  alluded  to.     The  great  blood  supply  required  for  all 

these  changes  is  provided  by  the  uterine  and  ovarian  arteries  which 

are  normally  very  large  in  proportion  to  the  size  of  the  organs. 

1  By  processes  of  diffusion  and  osmosis  as  in  the  lungs. 


358  ANATOMY  AND   PHYSIOLOGY 

Fig.  138  illustrates  the  way  in  which  they  are  disposed  in  order 
to  provide  for  the  increasing  area  to  be  supplied  and  for  the 
growth  of  the  fetus.  Their  tortuous  course  provides  for  a  greatly 
increased  distribution  to  constantly  enlarging  organs  without 
undue  stretching  of  the  vessels. 

During  the  first  three  or  four  months  (according  to  different 
authorities)  the  fetus  is  known  as  the  embryo. 

Expulsion  of  the  fetus  during  the  first  three  months  constitutes 
abortion;  from  the  fourth  to  the  sixth  months,  it  is  called  mis- 
carriage. After  six  months  it  is  possible  for  a  strong  fetus  to  go 
on  developing  after  expulsion  (although  exceedingly  uncommon 
at  that  date) ;  therefore,  from  that  time  until  term  (the  end  of  280 
days)  expulsion  constitutes  premature  delivery.  The  delivery  of 
the  child  is  usually  preceded  by  the  escape  of  amniotic  fluid. 

The  quantity  of  amniotic  fluid  is  about  one  liter.  Its  use 
is  to  provide  against  injury  from  sudden  jars  or  blows  during 
pregnancy,  to  allow  freedom  of  movement  on  the  part  of  the  fetus, 
to  preserve  the  flexibility  of  the  skin  of  the  fetus,  and  at  the  time 
of  parturition  to  aid  in  the  dilatation  of  the  cervix  of  the  uterus 
as  it  fills  a  pouch  of  the  amniotic  sac  which  is  forced  down  by 
uterine  contractions. 

Soon  after  the  expulsion  of  the  child,  the  placenta  is  separated 
from  its  attachment  to  the  uterus  by  the  contracting  walls  and 
later  is  expelled,  with  the  ruptured  and  emptied  sac. 

The  placental  site  is  now  bare  and  bleeding.  Large  blood 
spaces  or  sinuses  are  still  open,  left  by  the  detachment  of  the  pla- 
centa, although  rapidly  closing  if  the  uterus  becomes  well  con- 
tracted. 

Clinical  note. — The  great  advantage  of  a  well-contracted  uterus  is,  that 
it  guards  against  two  possible  dangers:  (i)  That  of  hemorrhage  from  the 
open  vessels;  (2)  (and  even  more  serious  if  possible)  that  of  infection  through 
this  wide  open  surface.  The  latter  is  the  reason  for  such  scrupulous  care 
which  is  demanded  in  the  nursing  of  obstetric  cases. 

The  lochia.  The  combined  decidua  vera  and  decidua  reflexa 
soften,  disintegrate  and  come  away  from  the  uterus  (with  the  blood 
which  is  oozing  from  the  interior)  as  lochia.  The  discharge  is 
known  at  first  as  the  lochia  rubra;  then,  when  it  is  thinner,  as  the 
lochia  serosa.  Third  and  lastly,  when  the  disintegrated  tissue  cells 


PLACENTA  PREVIA  359 

and  leucocytes  give  the  discharge  a  creamy  white  appearance,  it 
is  called  the  lochia  alba. 

Placenta  previa. — Wherever  the  ovum  attaches  itself  the  de- 
cidua  serotina  develops  to  form  the  maternal  part  of  the  placenta. 
Should  the  implantation  of  the  ovum  be  so  low  as  to  encroach 
upon  the  internal  os,  it  causes  a  placenta  previa. 

Ectopic  Gestation. — If  an  impregnated  ovum  begins  to  develop  at  any  point 
outside  the  uterus  this  constitutes  an  extra-uterine  or  ectopic  gestation.  Men- 
struation ceases  as  in  a  normal  pregnancy  and  a  decidua  vera  begins  to  form, 
but  is  often  shed  at  two  or  three  months.  Very  infrequently  the  develop- 
ment of  the  ovum  and  fetus  goes  on  to  term,  when  delivery  must  be  by  abdom- 
inal section,  but  the  usual  course  is  rupture  of  the  containing  part  and  inter- 
nal hemorrhage,  necessitating  an  operation  of  emergency. 

In  all  extra-uterine  or  ectopic  pregnancies  the  descriptive  name  is  derived 
from  the  abnormal  location,  as  tubal,  ovarian,  etc.,  etc. 

The  child-bearing  age  begins  at  puberty  or  the  time  of  develop- 
ment of  the  generative  organs  and  the  establishment  of  ovulation 
and  menstruation.  It  continues  until  the  climacteric  or  menopause 
which  marks  the  cessation  of  menstruation. 


CHAPTER  XXVI 
A  BRIEF  STUDY  OF  IMPORTANT  REGIONS 

THE  HEAD  AND  NECK 

The  scalp. — Observe  the  larger  arteries — the  supraorbital  in 
front,  the  temporal  and  posterior  auricular  at  the  sides,  and  occipital 
at  the  back — that  their  general  course  is  upward  toward  the  vertex, 
and  therefore  a  bandage  may  be  so  adjusted  around  the  head  as  to 
cut  off  the  blood  supply  to  a  great  extent. 

The  nerves  have  similar  names  and  take  a  similar  course. 

The  tense  temporal  fascia  covers  the  temporal  muscle  above 
the  zygoma. 

THE  FACE 

The  main  artery,  external  maxillary  (or  facial),  runs  obliquely 
upward  toward  the  side  of  the  nose;  its  course  is  tortuous,  so  that 
the  play  of  the  facial  muscles  will  not  interfere  with  the  passage 
of  the  blood  current.  The  facial  vein  is  lateral  to  the  artery  and 
not  very  close  to  it.  Pulsation  of  the  artery  may  be  felt  where  it 
crosses  the  lower  border  of  the  mandible,  about  one  inch  in  front 
of  the  angle. 

The  external  carotid  artery  bifurcates  in  the  substance  of  the 
parotid  gland  in  front  of  the  ear,  forming  the  temporal  and  internal 
maxillary  arteries.  The  pulsation  of  the  temporal  is  felt  as  it 
crosses  the  zygoma,  and  both  here  and  over  the  external  maxillary 
on  the  border  of  the  mandible,  the  character  of  the  heart's  action 
may  be  appreciated  while  the  patient  is  under  the  influence  of 
ether. 

The  motor  nerves  (facial  nerve)  come  through  the  parotid  gland 
and  radiate  on  the  side  of  the  face,  transversely  toward  the  nose, 
upward  toward  the  eye  and  forehead,  and  downward  toward  the 
neck. 

Sensory  nerves,  branches  of  the  trifacial  (trigeminus) ,  appear  at 

360 


STRUCTURES   OF   THE   NECK  361 

the  three  foramina  mentioned  elsewhere — supraorbital,  infra- 
orbital  and  mental — the  three  particularly  sensitive  spots  in  the 
front  of  the  face. 

Practical  note. — The  tongue  muscles  and  the  floor  of  the  mouth 
(mylo-hyoid  muscle)  are  both  connected  with  the  mandible. 
Therefore,  if  the  jaw  be  held  forward  and  upward,  it  will  control 
the  position  of  the  tongue  when  the  muscles  are  relaxed,  as  under 
ether.  Hence,  the  necessity  for  this  precaution,  to  prevent  the 
tongue  from  falling  back  into  the  throat. 


FIG.  232. — SUPERFICIAL  VESSELS  OF  HEAD. 

THE  NECK 

The  skin  of  the  back  of  the  neck  is  very  tough  and  the  fascia 
very  dense.  These  facts  account  for  the  pain  of  inflammation 
here,  due  to  the  consequent  pressure  upon  the  rather  numerous 
nerves,  as  in  carbuncle. 

The  spine  of  the  seventh  cervical  vertebra  is  always  easily  felt. 
This  is  the  vertebra  prominens. 

The  two  sterno-cleido-mastoid  muscles  are  conspicuous  at  the 
side  of  the  neck,  situated  near  each  other  at  their  origin,  and  di- 
verging above.  The  thyroid  cartilage  of  the  larynx  projects  in 
front — the  so-called  Adam's  apple.  The  external  jugular  vein  runs 
from  behind  the  ear  downward  toward  the  middle  of  the  clavicle, 
and  is  covered  by  the  pla'tysma  muscle.  It  is  sometimes  selected 
for  the  operation  of  "bleeding,"  or  phlebotomy,  and  the  incision 


362  ANATOMY  AND   PHYSIOLOGY 

to  expose  the  vein  is  made  across  the  muscle  fibers,  because  by 
their  retraction  the 'Vessel  is  well  uncovered  (Fig.  76). 

The  sternomastoid  and  trapezius  are  the  muscles  affected  in  the 
commonest  form  of  wry-neck  or  torticollis,  which  is  usually  due  to 
spasm  of  the  muscles. 

THE  TRIANGLES  OF  THE  NECK 

These  are  spaces  between  certain  muscles,  as  follows:  In  front 
of  the  ster no-mas toid  is  an  anterior  triangle  divided  by  the  superior 


FIG.  233. — TRIANGLES  OF  THE  NECK. 

C,  Carotid  triangle;  M,  muscular  triangle;  O,  occipital  triangle;  S,  subclavian 
triangle;  D,  digastric  triangle. 

belly  of  the  omo-hyoid  into  two,  called  the  carotid  and  muscular 
triangles;  behind  the  sterno-mastoid  is  &  posterior  triangle  divided 
by  the  inferior  belly  of  the  omo-hyoid  into  two,  called  the  occipital 
and  subclavian  triangles. 

In  the  muscular  triangle  is  the  common  carotid  artery,  with  the 
internal  jugular  vein  on  the  lateral  side  of  it,  and  the  vagus  nerve 
behind  them  both. 

In  the  carotid  triangle  the  same  structures  are  found,  but 


THE   THORAX  363 

here  the  artery  divides,  forming  the  external  and  internal  carotid 
arteries  at  about  the  level  of  the  upper  border  of  the  thyroid 
cartilage,  or  "Adam's  apple." 

Surgical  note. — The  carotid  is  called  the  triangle  of  election  because,  since 
the  vessels  are  near  the  surface,  the  surgeon  would  naturally  choose,  or  elect, 
this  place  for  the  operation  of  ligation.  In  the  muscular  triangle  the  vessels 
are  more  deeply  placed  and  covered  by  the  lower  portion  of  the  sterno-mas- 
toid.  Ligation  of  the  artery  would  be  done  here  only  under  necessity,  so  it 
is  called  the  triangle  of  necessity. 

Occipital  triangle. — The  occipital  artery  and  nerve  run  through 
this  triangle. 

Subclavian  triangle. — Most  important  structures  are  sub- 
daman  artery  and  vein,  brachial  plexus,  and  phrenic  nerve. 

Clinical  note. — Pressure  in  this  triangle,  close  to  the  clavicle,  will  be  felt 
by  the  nerves  of  the  brachial  plexus.  Pressure  downward  and  backward  close* 
to  the  sterno-mastoid  will  compress  the  subclavian  artery  against  the  first 
rib.  Its  pulsation  is  plainly  felt. 

Submaxillary  triangle. — This  is  a  small  space  marked  off  from  the  carotid 
by  the  digastric  muscle.  It  contains  the  submaxillary  gland  and  external 
maxillary  artery. 

THE  THORAX  AND  THORACIC  VISCERA 

The  bony  thorax  is  narrow  above  and  broad  below,  but  the 
proportions  are  reversed  in  the  completed  human  body  by  the 
presence  of  the  large  muscles  which  connect  the  upper  extremity 
with  the  thorax. 

Observe  the  transverse  ridge  on  the  sternum,  marking. Itihe, func- 
tion of  the  first  and  second  pieces  (the  manubrium  and  the  body). 
The  second  rib  joins  the  sternum  at  this  ridge  (Fig.  234). 

The  boundaries  of  the  completed  thorax  are  the  spinal  column 
at  the  back,  the  sternum  in  front,  and  the  ribs  at  the  sides,  with  the 
intercostal  muscles  in  the  intercostal  spaces  and  the  diaphragm  in 
the  floor.  It  is  covered  behind  by  the  muscles  of  the  back,  while 
the  anterior  serratus  is  on  the  side  and  the  pectoral  muscles  are  in 
front.  The  shoulder  blades  are  placed  behind  the  thorax. 

The  intercostal  arteries  and  nerves  are  protected  from  injury , by 
their  position  under  the  borders  of  the  ribs.  A  stab- wound  would 
have  to  be  directed  upward  to  reach  them. 

All  muscles  which  are  attached  to  the  ribs  are  muscles  of  res- 


364 


ANATOMY   AND   PHYSIOLOGY 


piration,  the  intercostals  having  considerable  power,  but  the  dia- 
phragm being  most  important.  When  it  contracts  it  is  depressed, 
increasing  the  depth  of  the  thoracic  cavity,  while  the  other  muscles 
broaden  the  cavity  by  lifting  the  ribs,  and  thus  room  is  made  for 
expansion  of  the  lungs  in  inspiration.  As  the  ribs  fall  and  the 
diaphragm  ceases  to  contract,  it  rises,  returning  to  its  dome  shape, 
and  thus  the  air  is  pressed  from  the  lungs  in  expiration.  These 


FIG.  234.— THORACIC  AND  ABDOMINAL  VISCERA,  ANTERIOR. — (Deaver.) 

two  acts  complete  a  respiration,  or  an  act  of  breathing,  which 
occurs  normally  about  eighteen  times  in  a  minute.  If  respiration 
is  very  difficult  other  muscles  are  called  into  play,  as  in  asthma, 
when  the  struggle  for  breath  is  so  great  that "  forced  inspiration"  is 
necessary. 

The  erector  spinae  muscles  are  always  on  duty,  to  steady  the 
spine  in  order  that  the  ribs  may  have  a  point  of  departure. 

The  cardiac  impulse  is  felt  (sometimes  it  may  be  seen)  between 


THORACIC   AND  ABDOMINAL  VISCERA  365 

the  fifth  and  sixth  ribs,  half  way  between  the  sternum  and  the 
nipple  line. 

The  mammary  gland  covers  the  front  part  of  the  spaces  from 
the  third  to  the  fifth  ribs.  It  lies  between  layers  of  the  superficial 
fascia  in  front  of  the  pectoralis  major  muscle. 

The  superior  opening  transmits  the  trachea,  esophagus,  and 
important  vessels  and  nerves.  The  floor  (or  diaphragm)  has  three 
openings — one  for  the  passage  of  the  aorta  and  thoracic  duct,  one 
for  •  the  inferior  vena  cava,  and  one  for  the  esophagus  and  vagus 
nerves. 

The  thoracic  viscera  are  the  esophagus,  trachea  and  bronchi, 
lungs,  and  heart.  The  esophagus  lies  close  to  the  spinal  column, 
and  the  trachea  is  in  front  of  the  esophagus,  dividing  into  the  large 
bronchi,  whose  branches  are  the  bronchial  tubes.  The  heart  and 
large  vessels  are  in  the  anterior  and  middle  part  of  the  thoracic 
cavity  (Fig.  234). 

The  heart  is  wrapped  in  the  pericardium,  and  each  lung  is 
wrapped  in  a  pleural  sac  which  is  placed  between  the  lung  and  the 
chest  wall.  An  incision  through  that  part  of  the  wall  which  is 
bounded  by  the  ribs  would  pierce  the  costal  pleura  and  open  the 
pleural  cavity.  A  wound  of  the  lung  would  injure  the  pulmonary 
pleura. 

The  large  nerves  in  the  thoracic  cavity  are  the  vagi,  lying  close 
to  the  esophagus,  the  sympathetic,  whose  branches  form  cardiac 
and  pulmonary  plexus,  and  the  two  phrenic  nerves,  right  and  left, 
running  down  on  either  side  of  the  pericardium  to  the  diaphragm. 

The  mediastinum  is  the  space  between  the  lungs.  In  it  all  of 
the  thoracic  viscera  except  the  lungs  are  situated. 

THE  ABDOMEN,  ABDOMINAL  VISCERA,  AND  PERITONEUM 

The  boundaries  of  the  completed  abdomen  are  the  spinal 
column  and  quadratus  lumborum  muscles  at  the  back,  the  hip-bones 
below,  the  rectus  muscles  in  front,  and  the  broad  fiat  muscles  at  the 
side.  The  diaphragm  is  its  roof.  The  transversalis  fascia  lines  the 
cavity,  and  the  peritoneum  is  within  the  fascia,  held  to  it  by  areolar 
tissue  called  subperitoneal  or  subserous  tissue. 

On  the  anterior  surface  of  the  abdomen  observe  the  outline 
made  by  the  lower  ribs,  between  the  thorax  and  abdomen,  the  two 
sides  meeting  in  the  subcostal  angle  just  below  the  sternum.  The 


366 


ANATOMY  AND   PHYSIOLOGY 


scrobiculus  cordis,  or  pit  of  the  stomach,  is  a  slight  depression  at 
the  very  point  of  the  subcostal  angle,  caused  by  a  weak  spot  in  the 
attachment  of  the  abdominal  muscles.  If  the  abdomen  is  greatly 
distended,  the  depression  disappears.  The  linea  alba  is  between 
the  two  rectus  muscles,  and  the  semilunar  lines  (or  line<z  semi- 
lunares)  are  at  the  sides  of  the  recti.  The  transverse  lines  (linea 
transversce)  may  be  seen  when  the  recti  contract. 

The  subcutaneous  inguinal  ring  is  just  above  the  tubercle  of  the 
pubic  bone;  the  abdominal  inguinal  ring  is  a  half  inch  above  the 


Tip  of  ensiform  cartilage 
Costal  border 


Upper  horizontal  plane 


Lower  horizontal  plane  A,  at 
level  of  tubercles  of  iliac 
crest 

Lower  horizontal  plane  B,  at 
evel  of  anterior  iliac  spines 


Vertical  plane  A,  from  middle 
of  Pou part's  ligament 

Vertical  plane  B,  at  outer 
border    of    rectus    (semi- 
lunar  line) 

Summit  of  symphysis  pubis 

FIG.  235. — DIAGRAM  OF  THE  ABDOMINAL  REGIONS. — (Morris.) 

middle  of  the  inguinal  ligament.  The  conjoined  tendon  is  behind 
the  subcutaneous  ring. 

The  abdominal  muscles  and  skin  are  supplied  by  the  lower 
intercostal  and  first  lumbar  nerves. 

The  regions  of  the  abdomen  are  outlined  in  the  following 
manner:  Imagine  a  horizontal  plane  passing  through  the  ab- 
domen at  the  level  of  the  tenth  costal  cartilage,  and  another  at  the 
level  of  the  anterior  superior  spine  of  the  ilium.  These  would 
divide  it  into  three  portions — upper,  middle,  and  lower.  Then 
imagine  two  vertical  planes  passing  through  the  middle  point  of 
the  inguinal  ligament  on  either  side,  and  dividing  each  of  these 
three  portions  into  three  regions,  making  nine  in  all. 


THE   PERITONEUM  367 

The  middle  region  is  called  the  umbilical,  having  the  umbilicus 
on  the  anterior  surface.  Above  that  is  the  epigastric,  and  below  it 
is  the  hypogastric.  At  the  sides  of  the  epigastric  region  are  the 
right  and  left  hypochondriac.  At  the  sides  of  the  umbilical  region 
are  the  right  and  left  lumbar;  and  at  the  sides  of  the  hypogastric 
region  are  the  right  and  left  iliac,  or  inguinal. 

The  abdominal  viscera  are  the  stomach,  intestines,  liver,  spleen, 
pancreas,  kidneys,  and  adrenal  bodies.  The  great  vessels  are  at  the 
back.  The  sympathetic  ganglia  are  at  the  sides  of  the  vertebrae, 
with  the  celiac  and  other  plexuses  situated  on  the  large  vessels. 

The  kidneys  are  behind  all  of  the  other  viscera,  and  the 
ureters  run  down  close  to  the  posterior  wall  of  the  abdomen  on  their 
way  to  the  bladder. 

The  receptaculum  chyli,  or  beginning  of  the  thoracic  duct,  is  in 
front  of  the  second  lumbar  vertebra.  The  inferior  vena  cava  lies  on 
the  right  side  of  the  aorta. 

The  principal  organ  in  the  epigastric  region  is  the  stomach;  in 
the  right  hypochondriac,  the  liver;  in  the  left  hypochondriac,  the 
spleen.  The  umbilical  region  is  occupied  mostly  by  small  intestines. 
The  right  and  left  kidneys  are  in  the  two  lumbar  regions,  with  the 
ascending  colon  in  front  of  the  right,  and  the  descending  colon  in 
front  of  the  left  kidney.  The  cecum  and  appendix  are  in  the  right 
inguinal  region;  the  bladder,  in  the  hypogastric. 

Each  region  contains  portions  of  several  viscera  in  addition  to  those  named. 
Scarcely  any  organ  save  the  spleen  and  cecum  can  be  said  to  belong  to  but  one 
region. 

The  peritoneum  is  a  closed  sac  of  serous  membrane  like  a 
water-bag,  which  is  placed  between  the  abdominal  wall  and 
abdominal  viscera.  It  is  practically  in  front  of  the  viscera,  and 
tucked  in  around  them  at  the  sides.  One  side  of  the  sac  is  closely 
applied  to  the  abdominal  wall,  and  is  called  the  parietal  peritoneum, 
while  the  other  side  is  fitted  to  the  viscera,  and  called  the  visceral 
peritoneum.  Normal  peritoneum  is  perfectly  transparent,  and  the 
viscera  are  plainly  seen  through  the  visceral  layer.  The  peritoneal 
cavity  contains  a  little  serous  fluid  and  nothing  else. 

An  incision  in  the  abdominal  wall,  including  the  parietal  per- 
itoneum, opens  the  peritoneal  cavity.  An  incision  into  one  of  the 
organs  involves  also  the  visceral  peritoneum,  with  these  exceptions: 


368  ANATOMY   AND   PHYSIOLOGY 

The  posterior  surface  of  the  liver. 

The  posterior  surface  of  the  ascending  colon.     The  kidneys. 

The  transverse  portion  of  the  duodenum.  The  front  of  the 
bladder  behind  the  symphysis.  These  parts  have  no  serous  layer. 

The  lowest  portion  of  the  peritoneal  cavity  is  in  the  pelvis, 
extending  down  about  three  and  a  half  inches  in  front  of  the 
rectum.  In  the  female  this  is  called  the  recto-uterine  fossa,  or 
pouch  of  Douglas.  In  the  male  it  is  the  recto-vesical  fossa. 

The  folds  of  the  peritoneum  which  are  connected  with  the 
stomach  are  called  omenta  (p.  148). 

The  folds  which  connect  the  intestines  to  the  abdominal  wall 
are  called  mesenteries  (p.  147). 

The  folds  which  connect  other  organs  to  the  abdominal  or  pelvic 
walls  are  called  ligaments.  Those  for  the  bladder  are  called  vesical 
ligaments. 

The  ligaments  of  the  liver  are  the  broad,  the  round,  the  coronary, 
and  the  two  lateral  ligaments,  which  connect  it  to  the  diaphragm 
and  the  anterior  abdominal  wall. 

Sometimes  certain  little  pockets,  or  fossae,  exist  in  the  perito- 
neum, behind  the  different  portions  of  intestine.  If  a  loop  or 
knuckle  of  bowel  slips  into  one  of  these  fossae  it  may  press  its  way 
through  it  and  pass  behind  the  peritoneal  sac.  This  is  a  retro- 
peritoneal  hernia. 

THE  ISCHIO-RECTAL  FOSSA 

This  is  a  space  between  the  ischium  and  the  rectum.  It  is 
filled  with  loose  connective  tissue  and  adipose,  and  a  few  vessels 
and  nerves  are  therein  contained.  The  skin  of  the  buttock  forms 
the  floor  of  the  fossa;  the  lower  part  of  the  rectum  is  the  medial 
wall;  the  fascia  of  the  obturator  muscle  forms  the  lateral  wall. 

Surgical  note. — If  infection  occur  in  this  region,  a  very  large  abscess 
might  result,  the  pus  burrowing  freely  in  the  loose  tissues.  Ischio-rectal 
abscess  is  often  caused  by  internal  fistula. 

THE  AXILLARY  SPACE 

The  axilla  is  the  armpit.  Its  shape  is  that  of  a  pyramid,  with 
the  apex  under  the  shoulder-girdle  at  the  level  of  the  first  rib,  the 
base  of  the  pyramid  being  the  floor  of  the  space  and  composed  of  the 


STRUCTURES   IN  AXILLARY   SPACE 


369 


skin  and  fascia  crossing  from  the  thorax  to  the  arm.  The  walls 
of  the  space  are  formed  by  muscles — the  serratus  (principally)  on 
the  medial  wall,  covering  the  ribs;  the  long  tendon  of  the  biceps 
in  its  groove  on  the  lateral  wall;  the  pectoral  muscles  in  the  anterior 
wall,  and  the  subscapularis,  latissimus  dorsi  and  teres  major  in  the 
posterior  wall. 

The  importance  of  this  space  is  due  to  the  large  vessels  and 
nerves,  and  the  lymph  nodes,  which  are  found  in  it.  The  vessels 
are  the  axillary  artery  and  vein;  the  nerves  are  the  brachial  plexus 
and  branches.  A  chain  of  superficial  lymph  nodes  lies  under  the 
border  of  the  pectoralis  major,  and  a  collection  of  deep  ones  is 
grouped  around  the  large  vessels;  there  are  also  a  few  near  the 
posterior  wall. 


Axillary  artery 


THE  ANTE-CUBITAL  SPACE 

A  triangular  space  in  front  of  the  elbow-joint. 

Boundaries. — The    brachio-radialis,    pronator    teres,    and    an 

imaginary    line     connecting 
the  two  epicondyles. 

Important  structures.— 
Biceps  tendon,  brachial  artery 
and  veins,  median  nerve.  The 


Median  nerve 
Brachial  artery 


Lateral  cord 


FIG.  236. — AXILLARY  SPACE. 
Axilla  laid  open  by  division  of  anterior 
wall. 


FIG.  237.— ANTE-CUBITAL  SPACE 

Pronator  muscle  divided  to  show 

ulnar  artery. 


artery  is  between  the  tendon  and  the  nerve,  lying  on  the  brach- 
ialis  muscle.  Tendon  on  lateral  side  of  artery — T-endon,  A-rtery, 
N-erve.  The  artery  divides  here. 


370  ANATOMY   AND   PHYSIOLOGY 

SCARP  A' s  TRIANGLE  (TRIGONUM  FEMORALE) 

This  triangle  is  on  the  front  of  the  thigh.  The  base  is  formed 
by  the  inguinal  ligament,  the  lateral  border  by  the  upper  half  of 
the  sartorius,  the  medial  border  by  the  adductor  longus,  and  the 
apex  by  the  crossing  of  these  two  muscles  on  the  medial  side  of 
the  thigh  at  about  the  middle. 


Femoral  artery 
Femoral  nerve 
Femoral  vein 


Deep  branch 


FIG.  238. — STRUCTURES  IN 
SCARPA'S  TRIANGLE;  PORTION  or 
SARTORIUS  REMOVED. 


FIG.  239. — POPLITEAL  SPACE. — (Holden.) 

a,  Biceps;  b,  peroneal  nerve;  c,  plantaris; 

d,  lateral  head  of  gastrocnemius;  e,  semi- 

tendinosus;/,  semimembranosus ;  g,  gracilis; 

h,  sartorius;  i,  medial  head  of  gastrocnemius. 


The  most  important  structures  in  the  triangle  are  the  femoral 
artery  and  vein  lying  side  by  side,  in  a  line  from  the  middle  of  the  ' 
base  to  the  apex.     The  femoral  nerve  and  branches  are  on  the 
lateral  side  of  the  artery. 

Order  of  structures  as  they  pass  under  the  inguinal  ligament. 
V-ein,  A-rtery,  N-erve,  the  vein  being  medialward. 


INGUINAL  AND  FEMORAL   CANALS  371 

HUNTER'S  CANAL  (ADDUCTOR  CANAL) 

This  is  a  passage  from  the  front  of  the  thigh  around  the  medial 
side  to  the  posterior,  beginning  at  the  apex  of  Scarpa's  triangle  and 
ending  in  the  popliteal  space  by  an  opening  in  the  adductor  magnus 
muscle.  The  femoral  artery  passes  through  this  canal,  with  the 
femoral  vein  on  the  medial  side  of  the  artery.  The  long  saphenous 
nerve  is  sometimes  within  the  canal  and  sometimes  outside  it. 

THE  POPLITEAL  SPACE 

This  is  a  deep  diamond-shaped  space  behind  the  knee-joint. 
Its  floor  is  formed,  from  above  downward,  by  the  popliteal  surface 
of  the  femur,  the  posterior  ligament  of  the  joint,  and  the  popliteus 
muscle.  The  boundaries  of  the  upper  half  of  the  space  are  made 
by  the  biceps  tendon  on  the  lateral  side,  and  the  semitendinosus 
and  semimembranosus  on  the  medial  side.  The  boundaries  of  the 
lower  half  are  the  lateral  and  medial  heads  of  the  gastrocnemius. 
These  muscles  are  all  very  prominent,  making  the  space  deep. 
The  popliteal  space  owes  its  importance  to  the  large  vessels  and 
nerves  which  it  contains — the  popliteal  artery,  the  popliteal  vein, 
and  tibial  and  common  peroneal  nerves.  They  are  all  deeply 
situated,  the  artery  being  the  deepest,  and  are  imbedded  in  adipose 
tissue  and  covered  with  strong  fascia,  being  thus  well  protected. 

THE  INGUINAL  RINGS  AND  INGUINAL  CANAL 

There  is  an  opening  in  the  aponeurosis  of  the  external  oblique 
muscle  just  above  the  pubic  bone,  which  is  called  the  subcutaneous 
inguinal  ring,  being  under  the  skin  in  the  inguinal  region. 

There  is  an  opening  in  the  transfer salis  fascia,  half  an  inch 
above  the  mid-point  of  the  inguinal  ligament.  This  is  called  the 
abdominal  inguinal  ring,  opening  into  the  abdominal  cavity  in 
the  inguinal  region.  The  passage  from  one  ring  to  the  other  is  the 
inguinal  canal. 

The  internal  oblique  and  transversus  muscles  form  the  conjoined 
tendon  immediately  behind  the  subcutaneous  ring,  and  their  lower 
muscle  fibers  arch  over  the  canal,  forming  its  upper  boundary. 

THE  FEMORAL  RING  AND  FEMORAL  CANAL 

The  femoral  ring  (annulusfemorale)  is  a  weak  place  in  the  pelvic 
wall,  under  the  inguinal  ligament,  where  the  femoral  vessels  do  not 


372  ANATOMY   AND   PHYSIOLOGY 

occupy  the  whole  of  the  space  in  their  sheath.  It  is  on  the  medial 
side  of  the  vein,  bounded  medially  by  Gimbernat's  ligament  (which 
is  at  the  medial  extremity  of  the  inguinal  ligament)  and  closed  by 
transversalis  fascia  only,  which  at  this  spot  is  called  the  crural 
septum  (septum  crurale). 

The  femoral  canal  extends  downward  from  this  ring  about 
three-quarters  of  an  inch  in  the  sheath  of  the  femoral  vessels. 

HERNIA 

Hernia  is  denned  as  a  tumor  formed  by  the  protrusion  of  con- 
tents of  a  cavity  through  its  wall.  This  may  occur  at  any  weak 
place  in  the  wall,  but  is  most  frequent  in  the  region  of  the  inguinal 
or  femoral  canals. 

If  any  structure  slips  accidentally  through  the  inguinal  canal  it 
forms  an  inguinal  hernia,  which  most  commonly  contains  a  loop 
of  bowel.  To  replace  the  bowel  or  other  structure  is  to  reduce  the 
hernia.  If  the  loop  cannot  be  replaced,  the  hernia  is  irreducible; 
and  should  it  become  so  distended  as  to  interfere  with  the  circula- 
tion, it  is  strangulated. 

In  direct  inguinal  hernia  the  contents  of  the  tumor  have  passed 
directly  through  the  conjoined  tendon  and  subcutaneous  ring.  In 
indirect  inguinal  hernia  the  contents  of  the  tumor  have  passed 
through  the  whole  length  of  the  inguinal  canal — that  is,  first  the 
abdominal  ring,  then  the  canal,  then  the  subcutaneous  ring. 

Umbilical  hernia  occurs  at  the  umbilicus;  ventral  hernia  at 
any  other  part  of  the  abdominal  wall,  except  one  or  both  rings. 

Diaphragmatic  hernia  occurs  at  a  weak  or  defective  point  in 
the  diaphragm  where  an  abdominal  structure  may  press  its  way 
into  the  thorax. 

In  femoral  hernia  the  bowel  or  other  structure  passes  through 
the  femoral  ring  into  the  femoral  canal  and  pushes  its  way  through 
the  femoral  sheath  at  the  oval  fossa,  or  saphenous  opening. 

Femoral  hernia  is  more  common  in  women — inguinal  hernia 
in  men. 

THE  EXTREMITIES  COMPARED 

Both  extremities  are  servants  of  the  head  and  trunk.  The 
lower,  being  fashioned  for  bearing  weight  and  also  for  walking  or 
running,  are  organs  of  locomotion,  transporting  the  body  from 
place  to  place  as  necessity  or  convenience  may  dictate;  while  the 


THE  EXTREMITIES  COMPARED 


373 


upper  are  organs  of  prehension,  since  they  can  reach  forth  and 
secure  various  things  which  are  required  for  the  use  of  the  body. 

Flexion  of  the  arm  is  accomplished  by  a  two-headed  muscle — 
the  biceps;  flexion  of  the  thigh  by  a  double  muscle,  the  ilio-psoas. 
Extension  of  the  elbow  is  accomplished  by  a  three-headed  muscle, 
the  triceps;  extension  of  the  knee  requires  a  powerful  four-headed 
muscle,  the  quadriceps. 

We  have  learned  to  apply  the  terms  medial  and  lateral  to  the 
body  while  in  the  ana- 
tomical position,  in  which 
the  forearm  is  supinated; 
therefore  the  thumb  is  said 
to  be  on  the  lateral  border 
of  the  hand,  but  the  leg 
cannot  be  supinated,  and 
the  great  toe  lies  on  the 
medial  border  of  the  foot 

Observe  that  the  toes 
of  civilized  man  are  freely 
flexed  and  extended,  but 
have  no  other  independent 
motions.  They  are  slightly 
affected  by  the  action  of 
plantar  muscles,  but  the 
foot  has  lost  the  suppleness 
it  might  have  had  without 
wearing  shoes.  The  fin- 
gers, however,  can  all  be 
moved  sideways;  the  me- 


Ulnar  nerve  and  artery 
Radial  nerve  and 
artery 


Branches  to  hand 


FIG.  240. — THE  FOREARM,  ANTERIOR. 


dian  line  of  the  hand  is  a  line  drawn  to  the  tip  of  the  middle  finger, 
and  the  digits  are  said  to  be  abducted  or  adducted,  according  as 
their  motion  is  from  or  toward  this  line. 

The  freedom  and  mobility  of  the  thumb  add  very  greatly  to  the 
usefulness  of  the  hand  in  grasping,  carrying,  etc.  If  the  fingertips 
approach  each  other,  the  hand  falls  into  a  gently  curved  position 
forming  a  cup,  the  "cup  of  Diogenes."  If  the  hand  be  closed 
forcibly  with  the  thumb  holding  the  fingers  against  the  palm,  it 
becomes  a  solid  irregular  mass,  the  "fist,"  and  so  an  ever-available 
weapon  of  offense  or  defense. 


374 


ANATOMY  AND   PHYSIOLOGY 


Suprascapular  nerve  and  artery 


The  shoulder  (and  whole  upper  extremity)  is  pulled  forward 

by  the  action  of  the  anterior 
serratus  on  the  shoulder  blade,, 
and  if  this  motion  is  accom- 
panied by  a  sudden  forcible 
extension  of  the  arm  and  fore- 
arm, that  is  "  striking  out  from 
the  shoulder." 

REVIEW  NOTES  CONCERNING 
THE  EXTREMITIES 


The  upper  extremity— 
From  the  shoulder  down,  the 
anterior  surface  is  the  flexor 
surface,  and  the  posterior  is 
the  extensor  surface  of  the 
extremity. 

Arm.  Anterior. — The  bi- 
ceps muscle,  with  the  median 
nerve  and  brachial  vessels  on 
its  medial  border.  Posterior. 
—Triceps  muscle,  with  radial 
nerve  in  the  groove  between 
the  two  humeral  heads. 

Forearm.  Anterior  (Fig. 
240). — Superficial  flexor  mus- 
cles and  the  round  pronator 
from  the  internal  epicondyle. 
Deep  flexor  muscles  from  shafts 
of  the  radius  and  ulna,  and 
median  nerve  between  the  su- 
perficial and  deep  groups. 
Posterior.  —  Extensor  muscles 
and  the  short  supinator  from 
the  external  epicondyle.  La- 
teral or  radial  side,  brachio- 
radialis  from  the  external 
epicondylar  ridge. 


br 


Posterior 
interosseous 


FIG.  241.— THE  ARM  AND  FOREARM 
'POSTERIOR. 


STRUCTURES   IN   THE   PALM  375 

The  hand.  Palm. — Observe  the  thenar  eminence  of  thumb 
muscles;  the  hypothenar  eminence  of  little-finger  muscles,  and 
between  them  the  hollow  of  the  hand,  where  the  long  flexor 
tendons  lie.  The  deep  palmar  arch  is  underneath  the  tendons; 
the  superficial  arch  lies  upon  them;  the  strong  palmar  fascia  holds 
the  tendons  in  a  compartment  lined  with  synovial  membrane. 
Dor  sum. — The  extensor  tendons  are  plainly  seen.  The  radial 
artery  may  be  felt  in  the  " anatomic  snuff-box"  (between  two  of  the 
extensors  of  the  thumb  as  it  winds  around  the  first  metacarpal  bone 
to  reach  the  deep  palm). 

The  long  flexor  and  extensor  tendons  of  the  fingers  may  be 
plainly  felt  and  seen  at  the  wrist. 

The  lower  extremity. — The  inguinal  ligament  stretches  from 
the  spine  of  the  ilium  to  the  tubercle  of  the  pubes. 

The  femoral  artery,  femoral  vein,  and  femoral  nerve  pass  under 
the  ligament,  the  artery  lying  on  the  psoas  muscle.  Their  order 
from  the  medial  side  outward  is  V-ein,  A-rtery,  N-erve. 


From  the  hip  down,  the  anterior  surface  is  alter- 
nately flexor  and  extensor 


The  posterior  surface  is  exactly  the  reverse. 


Flexor  for  hip. 
Extensor  for  knee. 
Flexor  for  ankle. 
Extensor  for  toes. 
Extensor  for  hip. 
Flexor  for  knee. 
Extensor  for  ankle. 
Flexor  for  toes. 

Thigh. — Anterior-  and  sides  of  the  femur  are  covered  by  the 
quadriceps  muscle,  which  extends  the  knee.  The  sartorius  muscle 
crosses  from  the  anterior  spine  of  the  ilium  to  the  middle  of  the 
medial  side  of  the  thigh  and  down  to  the  tibia,  and  when  it  con- 
tracts it  makes  a  depression  rather  than  an  elevation,  because  it 
binds  the  soft  tissue  under  it.  Posterior. — The  biceps,  semi- 
membranosus  and  semitendinosus  muscles  flex  the  knee;  they  are 
hamstring  muscles,  making  the  upper  boundaries  of  the  popliteal 
space.  The  medial  side  of  the  thigh  is  occupied  by  the  adductor 
muscles,  with  the  obturator  nerve  and  vessels. 

Leg.  Anterior. — The  medial  surface  of  the  tibia  is  called  sub- 
cutaneous because  it  is  not  covered  by  muscles;  the  long  saphenous 
nerve  and  vein  extend  the  whole  length  of  this  surface. 

The  anterior  tibial  muscles  occupy  the  neighboring  surfaces  of 


376 


ANATOMY   AND   PHYSIOLOGY 


Sciatic  nerve 


Anterior  tibial 
nerve 


Peroneal  nerve 


I Ant.  tib.  artery 


Tibial  nerve 
Post.  tib.  artery 


FIG.  242.— THE  FEMORAL  ARTERY.  FIG.  243.— THE  SCIATIC  NERVE. 


FEMORAL  AND   SCIATIC  NERVES  377 

the  tibia  and  fibula,  and  their  tendons  all  pass  in  front  of  the 
ankle-joint  to  flex  it  (dorsal  flexion).  The  lateral  side  of  the  leg  is 
occupied  by  the  peroneus  longus  and  brevis  whose  tendons  pass 
behind  the  lateral  malleolus  to  extend  the  foot.  They  are  ac- 
companied by  the  superficial  peroneal  nerve  which  supplies  them 
(ant.  tibial  nerve). 

The  long  tendons  for  the  toes  are  plainly  visible  on  the  dorsum 
or  top  of  the  foot,  and  also  those  of  the  short  flexor,  which  has  four 
tendons  belonging  to  the  four  medial  toes. 

Posterior. — The  calf  muscles,  which  lift  the  heel,  completely 
cover  the  deep  muscles  whose  tendons  pass  into  the  sole  of  the  foot 
behind  the  medial  malleolus  to  extend  the  foot. 

The  deep,  or  posterior  tibial  muscles,  lie  between  tibia  and  fibula 
bound  down  by  the  deep  transverse  fascia  of  the  leg. 

The  large  nerves  for  the  lower  extremity  are  the  femoral  and 
the  sciatic. 

The  femoral  comes  under  the  inguinal  ligament  into  Scarpa's 
triangle  and  immediately  breaks  up  into  branches  which  supply 
the  structures  of  the  thigh,  the  long  saphenous  nerve  being  the 
only  branch  to  go  below  the  knee.  It  runs  all  the  way  to  the 
medial  border  of  the  foot. 

The  sciatic  comes  through  the  great  sciatic  notch,  descending 
between  the  great  trochanter  and  the  tuber  of  the  ischium  into 
the  back  of  the  thigh,  to  divide  at  the  popliteal  space  into  the 
tibial  and  the  common  peroneal  nerves.  The  tibial  nerve  continues 
under  the  calf  muscles  and  into  the  plantar  region.  The  peroneal 
nerve  winds  around  the  head  of  the  tibia  to  the  front  of  the 
leg,  sending  the  deep  peroneal  branch  to  the  anterior  muscles,  and 
dorsum  of  the  foot. 

LOCATION  OF  LARGE  VESSELS  AND  NERVES  IN  THE 
EXTREMITIES 

The  vessels  and  nerves  are  so  placed  as  to  be  in  the  least 
possible  danger  from  pressure  or  blows.  For  example,  the  axillary 
vessels  and  brachial  plexus  are  deep  in  the  axilla;  the  brachial 
vessels  and  median  and  ulnar  nerves  are  on  the  least  exposed  side 
of  the  arm,  and  they  pass  in  front  of  the  elbow-joint  where  the 
motion  of  the  joint  will  not  interfere  with  them.  So  in  the  fore- 


378  ANATOMY  AND   PHYSIOLOGY 

arm,  the  radial  and  ulnar  arteries  and  nerves  are  protected  by 
muscles.  At  the  wrist  they  also  pass  into  the  hand  on  the  flexor 
surface. 

The  large  nerve  which  passes  behind  the  humerus,  the  radial 
nerve,  is  covered  by  the  thick  triceps  muscle  and  winds  to  the  front 
of  the  bone  to  pass  the  elbow-joint  on  its  way  to  the  forearm. 

The  femoral  vessels  and  nerves  are  in  the  fold  or  flexure  of  the 
groin,  and  they  wind  around  the  femur  to  reach  the  flexor  surface 
of  the  knee.  Both  anterior  and  posterior  tibial  arteries  are  well 
protected  by  muscles — the  posterior  tibial  especially — which  is 
under  the  calf  muscles  and  the  transverse  fascia  of  the  leg.  As  it 
passes  the  ankle-joint  it  lies  under  strong  ligaments  on  the  medial 
side  of  the  joint,  where  it  would  not  be  put  on  the  stretch  during 
any  natural  movement  of  the  foot  nor  exposed  to  blows.  Again, 
the  large  arteries  of  the  hand  are  in  the  palm,  while  those  of  the 
foot  are  in  the  sole. 

POINTS  FOR  COMPRESSION  or  LARGER  ARTERIES 

The  temporal,  on  the  zygoma. 

The  external  maxillary,  on  the  lower  border  of  the  mandible. 

The  subclavian  on  the  first  rib,  behind  the  clavicle  (downward 
and  backward). 

The  axillary,  on  the  humerus,  in  the  lower  part  of  the  axilla. 

The  brachial,  on  the  humerus,  under  medial  border  of  the  biceps 
muscle. 

The  radial  and  ulnar,  on  the  bones  of  same  name,  in  the  lower 
part. 

The  femoral,  against  the  ramus  of  the  pubic  bone,  just  below 
the  inguinal  ligament. 

Note. — The  subclavian  artery  is  crossed  by  the  scalenus 
anticus  muscle  which  divides  it  into  first,  second,  and  third  por- 
tions. The  axillary  artery  is  crossed  by  the  pectoralis  minor 
muscle,  which  divides  it  into  first,  second,  and  third  portions.  The 
common  carotid  artery  is  crossed  by  the  omo-hyoid  muscle;  the 
portion  below  the  muscle  is  in  the  muscular  triangle  of  the  neck; 
the  portion  above  is  the  carotid  triangle. 


CHAPTER  XXVII 
REFERENCE  TABLES 


379 


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GLOSSARY 


Abdomen.     From  a  word  meaning  to  conceal.     The  abdomen  contains  or  conceals  the 

abdominal  organs. 
Abduction.     From  a  Latin  word  meaning  to  lead  from.     The  abducens  muscle  leads,  or 

turns,  the  eye  from  the  median  line. 
Acetabulum.     A  small  vessel  or  cup  for  vinegar.     The  name  given  to  the  round 

depression  or  cavity  of  the  hip  bone  or  os  coxae,  for  the  head- of  the  femur. 
Acid.     Sour.     Acids  redden  blue  litmus  paper. 
Accommodation.    The  adjusting  or  focussing  of  the  eye  for  vision  at  different 

distances. 

Acromegaly.     A  disease  characterized  by  over-growth  of  the  face  and  extremities. 
Acromion.     From  Greek  words  meaning  summit  and  shoulder.     The  process  of  bone 

at  the  highest  point  of  the  shoulder. 
Adduction.    Leading  toward. 

Adenoid.     Resembling  a  gland  or  aden.     A  gland-like  growth  in  the  naso-pharynx. 
Adipose.     Fatty.     Fat. 

Afferent.     Bearing  toward.    Afferent  vessels  enter  organs. 
Ala.     A  wing.     (Plural,  ala). 
Alimentary.     Pertaining  to  food  or  aliment,  as,  the  alimentary  tract,  which  contains 

the  food  until  it  is  digested. 

Alkaline.     Opposite  of  acid.     An  alkali  turns  red  litmus  paper  blue. 
Alveolus.     The  border  of  the  jaw  bone,  named  for  the  cavities  which  contain  the 

teeth.     (Alveolus^  a  little  hollow.) 

Ameba.     A  one-celled,  jelly-like  living  being,  which  constantly  changes  its  form. 
Ameboid  movements.     Movements  which  cause  a  change  of  form,  like  those  of  the 

ameba. 

Amphoteric.    Like  both.     Applied  to  fluids  which  possess  certain  qualities  resem- 
bling both  alkalies  and  acids. 
Amyloid.    Starchy  or  starch  like. 

Amylopsin.     The  starch-digesting  ferment  of  pancreatic  fluid. 
Anastomosis.     The  opening  of  one  vessel  into  another.    Literally — to  bring  to  a 

mouth. 

Ancon.     The  elbow.     Anconeus,  a  muscle  of  the  elbow-joint. 
Annulus.     A  little  ring.     (A  nnulus  ovalis,  the  oval  little  ring  of  the  heart.) 
Anonyma.     Without  a  name. 

Antebrachium.     The  forearm.     From  ante,  before,  and  brachium,  the  arm. 
Antecubital.     Applied  to  the  space  in  front  of  the  elbow.     From  ante,  before,  and 

cubit,  the  forearm. 

Antrum.     A  cave.     The  hollow  in  the  maxilla  is  called  the  Antrum  of  Highmore. 
Aorta.     The  largest  artery  in  the  body. 
Apnea.     Suspension  of  breathing. 

Aponeurosis.     A  layer  of  strong  white  fibrous  tissue  (meaning  from  a  tendon). 
Aqueous.     Watery,  from  aqua,  water. 
Arachnoid.     Like  a  spider's  web,  for  fineness.     One  of  the  membranes  of  the  brain 

and  spinal  cord. 
Areolar.     Having  little  spaces. 
Arterio-sclerosis.     Hardening  of  the  arteries. 
Artery.     A  vessel  carrying  blood  away  from  the  heart. 
Arthrosis.     A  joint  or  articulation. 
Arytenoid.     Shaped  like  the  mouth  of  a  pitcher. 
Assimilation.     The  taking  up  of  nutriment  by  the  body  tissues,  in  such  a  manner 

that  it  becomes  a  part  of  them. 
Asphyxia.     A  condition  in  which  the  blood  is  deprived  of  oxygen. 

389 


3QO  GLOSSARY 

Atlas.     A  fabled  giant  who  bore  the  globe  upon  his  shoulders.     The  first  cervical 

vertebra,  upon  which  the  skull  rests. 
Atrium.     A  hall,  a  chamber  of  the  heart  where  blood  enters. 
Atrophy.     Wasting.     From  a  Greek  word  signifying  want  of  nourishment. 
Auricular.     Shaped  like,  or  belonging  to,  an  ear  or  auricle. 
Axis.     The  second  cervical  vertebra.     Named  because  of  the  pivot  around  which  the 

atlas  revolves  (like  a  wheel  around  an  axis). 
Axone.    An  axis.    The  essential  part  of  a  nerve  fiber. 

Azygos.     Without  a  yoke.     The  name  of  certain  vessels  which  are  not  in  pairs. 
Biceps.     Having  two  heads,  as  the  biceps  femoris;  biceps  brachii. 
Bicuspid.     Having  two  points  or  cusps.     A  bicuspid  tooth. 
Bone  corpuscle.     A  formative  cell  of  bone  tissue. 
Brachialis.     Belonging  to  the  arm,  or  brachium. 
Bronchus.     An  air  tube.     (Plural,  bronchi.}     The  smallest  air  tubes  are  called 

bronchioles. 

Buccinator.     From  a  word  meaning  trumpet.     The  blowing  or  trumpeting  muscle. 
Bursa.    Literally,  a  purse.    The  burses  are  small  sacs  containing  fluid  and  found  in 

the  fascia  under  skin,  or  muscles,  or  tendons. 
Calcaneus.     The  heel  bone.     The  tendo  calcaneus,  or  tendo  Achillis,  is  attached  to 

the  calcaneus. 
Calculus.     A  stone-like  body  formed  in  some  fluid  of  the  body.     Renal  calculus,  in 

the  kidney;  biliary  c.,  in  the  gall-bladder,  etc. 
Callus.     A  thickened  portion  of  the  skin.     The  material  thrown  out  (provisional 

callus)  for  the  repair  of  fractured  bone,  to  become  the  permanent  callus  when 

the  bone  is  completely  ossified. 

Cancellous.     Resembling  lattice  work.     A  cancellous  or  spongy  bone. 
Canine.     Resembling  a  dog.     Canine  teeth,  like  a  dog's  teeth. 
Canthus.     The  angle  at  the  meeting  of  upper  and  lower  eyelid;  plural  canthi. 
Capillary.    Resembling  a  hair  in  size.     (Capillus,  a  hair.) 
Capitellum,  or  capitulum.     A  little  head,  an  eminence  on  the  lower  extremity  of  the 

humerus. 

Capsule.     A  structure  which  encloses  an  organ  or  part.     (The  capsule  of  a  joint.) 
Carbo-hydrate.     A  substance  composed  of  carbon  and  water;  sugars  and  starches. 
Cardiac.     Belonging  to  the  heart  or  cardia. 
Caries.     Decay  of  bone.     Carious,  decaying. 
Carotid.     The  name  of  the  large  arteries  of  the  neck,  once  thought  to  cause  sleep. 

From  a  Greek  word  meaning  to  produce  sleep. 
Caruncle.     A  small  soft  projecting  tumor.     Urethral  caruncle,  a  minute  tumor  of  the 

urethral  mucous  membrane,  made  up  mostly  of  nerves  and  vessels. 
Casein.     The  proteid  or  cheesy  part  of  milk. 
Cast.     An  albuminous  structure  moulded  in  tubular  form. 
Cauda  equina.     A  horse-tail.     The  name  given  to  the  bundle  of  spinal  nerves  in  the 

lower  portion  of  the  spinal  canal. 

Cecum.     Blind.     The  blind  pouch  at  beginning  of  the  large  intestine. 
Celiac  (cceliac).     Pertaining  to  the  celia  or  belly. 
Center.     In  the  nerve  system,  a  center  is  a  collection  of  gray  cells.     The  central 

nerve  system  comprises  the  brain  and  spinal  cord,  which  contain  the  large  nerve 

centers.     Central  convolutions  contain  a  majority  of  motor  centers. 
Centrifugal.     Referring  to  a  force  which  is  exerted  from  the  center  outward;  a 

_  centrifugal  nerve  conducts  impulses  from  a  center. 
Centripetal.     Applied  to  a  force  which  seeks  a  center;  a  centripetal  nerve  conducts 

impulses  to  a  center. 
Cerebellum.    Little  brain. 
Cerumen.     The  wax  of  the  ear.     (Cera,  wax.) 
Cervix.     Neck.     Cervical,  belonging  to  or  resembling  a  neck. 
Choana.     A  funnel.     The  choana  are  the  posterior  openings  from  the  nose  into  the 

pharynx.  , 

Choroid.    Like  the  chorion,  which  is  a  fetal  membrane  bearing  blood-vessels. 
Cicatrix.     A  scar.     It  is  formed  of  fibrous  connective  tissue. 

Cilia.     Eyelashes.     Ciliated,  having  tiny  hair-like  projections,  as  ciliated  epithelium. 
Ciliary.     The  ciliary  region  of  the  eye  presents  radiating  lines,  caused  by  folds  of  the 

tissues  composing  it  (ciliary  processes}. 


GLOSSARY  391 

Circumduction.    Leading  around.     This  is  the  motion  made  when  a  part  is  moved 

around  in  a  circle,  one  end  being  stationary.     The  extremities,  the  digits  and 

the  head,  may  be  circumducted. 

Circumflex.     To  bend  around.     Circumflex  arteries  wind  around  the  arm  or  thigh. 
Circumvallate.     Walled  around.     The  circumvallate  papillae  at  the  base  of  the 

tongue  are  encircled  by  a  ridge. 

Clavicle.     The  clavicula,  which  resembles  a  very  ancient  key. 
Climacteric.    Literally,  the  round  of  a  ladder.     Any  time  of  life  when  the  system  is 

believed  to  undergo  marked  and  permanent  changes;  usually  applied  to  the 

time  of  the  cessation  of  menstruation. 
Coagulation.     From  coagulare,  to  curdle.     The  clotting  of  blood.     Coagulum,  a 

blood  clot. 
Coccyx.     A  cuckoo's  beak.     The  bone  at  the  end  of  the  spinal  column,  named  from 

its  shape. 
Cochlea.     A  conch-shell.     A  cavity  of  the  internal  ear  resembling  a  snail-shell  in 

form. 
Collateral.     From  words  meaning  side  and  together.     Collateral  circulation  is  secured 

by  the  union  of  branches  of  two  vessels,  whereby  the  main  current  of  fluid  may 

be  carried  by  this  side  route  if  necessary. 
Colliquative.    Literally — a  melting  together.     Colliquative  stools  are  profuse  and 

watery. 
Commissure.     A  placing  together.     A  commissure  connects  two  parts  of  an  organ, 

as  the  commissures  of  the  brain. 
Communis.     Common.     Applied  to  a  muscle  whose  tendons  are  common  to  several 

organs. 

Concha.    A  shell. 

Condyle.     A  knuckle.     A  rounded  eminence  of  bone. 

Conjunctiva.     Connecting.    The  mucous  membrane  which  connects  the  under  sur- 
faces of  the  eyelids. 
Conoid.     Shaped  like  a  cone. 
Convoluted.     Twisted. 
Co-ordinate.     From  words  meaning  together,  and  to  order  or  regulate.     Co-ordination 

is  the  systematic  acting  together  of  several  parts. 
Coracoid.    Like  a  crow's  beak.     The  coracoid  process  of  the  scapula. 
Corium.     Leather.     The  deep  portion  of  the  skin  from  which  leather  is  made. 
Cornea.     Horny.     The  tough  transparent  membrane  in  the  anterior  of  the  eyeball. 
Cornua.     Plural  of  cornu,  a  horn. 

Coronal  or  coronoid.     Pertaining  to,  or  resembling  a  crown. 
Coronary.     The  coronary  arteries  encircle  the  base  of  the  heart. 
Corpus  callosum.     The  transverse  commissure  of  the  cerebral  hemispheres. 
Corpuscle.     A  little  body.     A  blood  cell.     Malpighian  corpuscle,  a  structure  in  the 

kidney.    Lymph  corpuscle,  a  cell  formed  in  a  lymph  gland. 
Corpus  luteum.     Yellow  body.     The  substance  formed  in  a  ruptured  Graafian 

follicle  of  the  ovary. 

Cortex.     Bark.     The  superficial  layer,  as  the  cortex  of  the  brain. 
Costal.     Relating  to  a  rib  or  costa. 

Coxae.     Plural  of  coxa,  the  hip;  also  the  genitive  form,  as  os  coxes,  the  bone  of  the  hip. 
Cranium.     The  part  pf  the  skull  which  contains  the  brain. 
Crest.     A  ridge  of  bone,  either  on  a  surface  or  at  the  border. 
Cretinism.     The  condition  of  a  cretin  or  undeveloped  person,  both  mentally  and 

physically. 

Cribriform.     Resembling  a  sieve. 

Cricoid.    Like  a  ring.     The  cricoid  cartilage  of  the  larynx  is  shaped  like  a  seal  ring. 
Crucial.     Like  a  cross.     The  crucial  ligaments  cross  each  other. 
Crural.     Belonging  to  or  like  the  lower  extremity,  from  crus,  a  leg;  as  the  crural 

nerve,  the  crura  (or  legs)  of  the  diaphragm. 
Cystic.     Relating  to  a  cyst,  or  a  sac  containing  fluid  (cystic  duct).     A  cystic  ovary  has 

cysts  developed  from  its  substance. 
Deglutition.     The  act  of  swallowing. 
Deltoid.     Shaped  like  the  Greek  letter  delta,  A. 
Dental.     From  dens,  a  tooth,  belonging  to  a  tooth. 
Dentated.     Having  points  which  resemble  teeth. 
Dentition.     The  eruption  or  "cutting"  of  the  teeth. 


3Q2  GLOSSARY 

Diapedesis.     A  jumping  through.     The  passing  of  blood  cells  through  the  walls  of 

capillaries. 

Diaphoretic.     A  remedy  which  increases  the  amount  of  perspiration. 
Diaphragm.     A  wall  across  a  space.     The  muscle  which  separates  the  cavity  of  the 

thorax  from  that  of  the  abdomen. 
Diaphysis.     The  greater  part  of  the  shaft  of  a  bone. 
Diarthrosis.     A  movable  joint. 
Diastole.     A  Greek  word  meaning  a  drawing  apart.     The  dilation  of  the  chambers  of 

the  heart. 

Digastric.     Double  bellied  as  the  digastric  muscle. 
Digit.     A  finger  or  toe. 
Distal.     Farthest  from  the  head  or  trunk. 
Diuretic.     A  remedy  which  increases  the  quantity  of  urine. 
Dorsal.     Belonging  to  the  dorsum,  or  back. 

Duodenum.     Meaning  twelve.     The  duodenum  is  twelve  finger-widths  long. 
Dura  mater.     Hard  mother.     The  fibrous  outer  membrane  of  the  brain  and  spinal 

cord. 

Dyspnea.     Difficult  breathing. 

Edema.     Swelling  caused  by  effusiori  of  serous  fluid  into  areolar  tissues. 
Efferent.     Bearing  from.     Efferent  vessels  leave  organs. 

Effusion.     An  abnormal  pouring  out  (or  secreting)  and  collection  of  fluid  in  the  body. 
Element.     A  substance  which  cannot  be  divided  into  simpler  substances. 
Eliminate.     From  words  meaning  without  the  threshold.     To  excrete  substances 

which  are  useless. 
Embryo.     The  ovum  and  structures  belonging  to  it  constitute  the  embryo,  until  the 

fourth  month  of  intrauterine  life. 
Endo-.     Within.     Endocardium,  within  the  heart.     Endothelium,  the  epithelium  of 

the  interior  of  circulatory  organs. 
Endomysium.     The  sheath  of  a  muscle-fiber. 
Endpsteum.     The  lining  of  medullary  canals  in  long  bones. 
Ensiform.     Sword-shaped.     The  appendix  of  the  sternum. 
Enteric.    Pertaining  to  the  enter  on  or  intestine,  as  enteric  or  typhoid  fever. 
Enzyme.     Any  ferment  in  a  digestive  fluid. 
Epi.     Upon,  as  epi-condyle,  epidermis,  epiglottis. 
Epimysium.     The  connective-tissue  muscle  sheath. 
Epiphysis,     A  part  of  a  bone  which  is  formed  independently,  and  joined  later  to 

complete  the  whole  bone. 
Epithelial.     Pertaining  to  epithelium. 

Epithelium.    The  uppermost  or  superficial  layer  of  cells  of  a  body  surface. 
Erythrocyte.     A  red  cell  of  the  blood.    A  red  corpuscle. 
Esophagus.     From  a  Greek  word  meaning  to  carry  food.     The  esophagus  transmits 

food  from  pharynx  to  stomach. 

Ethmoid.     Sieve-like.     The  ethmoid  bone  has  many  openings  on  its  surface. 
Eversion.     Turning  outward.     To  evert  an  eyelid  is  to  fold  it  back  so  as  to  expose  the 

interior  surface. 

Excretion.     A  waste  substance  to  be  removed  from  the  body.     The  process  of  re- 
moving waste  from  the  tissues. 

Extension.     Stretching  out  or  extending.     (Bending  backward  is  over-extension.) 
Exudate.     A  collection  of  material  which  has  filtered  through  the  walls  of  vessels  into 

surrounding  tissues. 
Falciform.     Sickle-shaped. 
Falx.     A  sickle. 
Fascia.     A  band;  plural,  fascia.     The  tissue  which  binds  organs  or  parts  of  organs 

together. 
Fauces.     From  the  Latin  word  faux,  the  throat.     Isthmus  of,  the  space  bounded  by 

the  soft-palate,  tonsils  and  tongue.    Pillars  of,  the  folds  connecting  the  soft 

palate  with  the  tongue  and  pharynx.     (The  tonsil  is  between  the  pillars  of 

either  side.) 

Femoral.     Belonging  to  the  femur  or  thigh  bone. 
Fetus.     After  the  fourth  month,  the  embryo  becomes  the  fetus. 
Fibrin.     A  proteid  substance  of  the  blood  which  causes  coagulation. 
Filiform.     Thread-like  in  shape,  slender;  as  filiform  papillae  of  the  tongue. 
Fimbria.     A  fringe;  fimbriated,  having  a  fringe-like  appearance. 


GLOSSARY  393 

Fissure.     A  cleft  or  groove,  as  a  fissure  of  the  brain  surface. 

Fistula.     A  pipe.     A  tube-like  passage  caused  by  disease. 

Flava.     Plural  of  flavus,  yellow.    Applied  to  elastic  ligaments  which  contain  yellow 

elastic  tissue. 

Flexion.     Bending.    Flexure,  a  bend. 

Follicle.     A  very  small  sac  (or  bag)  containing  a  secretion. 
Fontanelle.    A  little  spring.    A  membranous  spot  in  the  infant's  skull;  the  name 

suggested  by  the  rising  and  falling  caused  by  the  child's  respirations. 
Foramen.     A  hole.     Plural,  foramina. 
Fossa.     A  depression  or  concavity. 
Fourchette.     A  little  fork. 
Fovea.    A  small  pit.    Thefovea  centralis  is  a  tiny  depression  in  the  macula  lutea  of 

the  retina. 
Frenum.     A  curb  or  bridle.    The  frenum  lingua  is  the  fold  of  mucous  membrane 

attaching  the  tongue  to  the  floor  of  the  mouth. 
Fundus.    The  base. 

Fungiform.     Shaped  like  a  fungus  or  mushroom. 
Fusiform.     Spindle-shaped. 

Ganglion.    A  knot.     (Plural,  ganglia.}  ^  A  collection  of  nerve  cells. 
Gaster.    The  stomach.    Gastric,  belonging  to  the  stomach  or  gaster. 
Gastrocnemius.    The  belly  of  the  leg.    The  prominent  muscle  of  the  calf  of  the  leg. 
Genioglossus.     Belonging  to  the  chin  and  tongue. 
Genu.    A  knee. 

Glabella.    A  little  smooth  space.    The  smooth  space  between  the  eyebrows. 
Gladiolus.    A  little  sword.    The  body  of  the  sternum. 
Gland.    A  collection  of  cells  which  can  form  a  secretion  or  an  excretion. 
Glans.    The  head  of  the  clitoris  or  penis. 

Glenoid.     Having  the  form  of  a  shallow  cavity.    Belonging  to  a  cavity. 
Glossopharyngeal.    Belonging  to  the  tongue  and  pharynx. 
Glottis.    The  upper  opening  of  the  larynx.    Epiglottis,  the  leaf-shaped  cartilage 

upon  the  upper  border  of  the  larynx. 
Glucose.    Grape  sugar.    Dextrose. 
Gluteus.     Belonging  to  the  gluteus  or  buttock. 
Glycogen.    A  white  substance  formed  principally  in  the  liver.     Sometimes  called 

animal  starch. 

Gustatory.    Associated  with  the  sense  of  taste. 
Gyre.     From  gyrus,  a  circle.    A  convolution  (referring  to  the  convolutions  of  the 

brain). 

Haversian.    Name  applied  to  the  tiny  canals  in  bone  tissue,  from  the  English  anato- 
mist Havers. 

Hepatic.    Belonging  to  the  liver  or  kepar. 
Hemoglobin.    The  oxygen-carrying  substance  of  red  blood  cells,  to  which  their  color 

is  due. 

Hemolysis.     Destruction  of  red  blood  cells. 
Hemorrhoidal.     From  a  word  meaning  flowing  with  blood.     Pertaining  to  a  hemor- 

rhoid  or  pile. 
Hilum.    Literally,  a  little  thing.    Applied  to  the  depression  where  vessels  enter  and 

leave  an  organ. 

Hormones.     Chemical  substances  (character  unknown),  formed  (probably)  in  duct- 
less glands,  and  conveyed  by  the  blood  to  other  organs,  to  influence  thei 

activity. 

Hyaline.    Resembling  glass.     Hyaloid  has  a  similar  meaning. 
Hydration.     Saturating  with  water. 
Hydrocephalus.    A  collection  of  fluid  either  within  the  ventricles  or  outside  of  the 

brain. 

Hyoid.     U-shaped,  as  the  hyoid  bone. 
Hypertrophy.    Over-growth.    Derived  from  two  Greek  words  meaning  too  much 

nourishment. 
Hypochondrium.     Under  the  cartilage.    The  hypochondriac  region  is  under  the 

cartilages  of  ribs.     (Hypo-  under.) 

Hypodermoclysis.     Injection  of  fluid  under  the  skin — in  quantity. 
Hypogastric.    Under  the  stomach. 
Hypoglossal.     Under  the  tongue. 


394  GLOSSARY 

Hypothenar.     Under  the  palm  or  sole.    The  eminence  on  the  medial  side  of  the 

palm  or  the  sole. 
Ileum.     A  roll  or  twist;  the  portion  of  small  intestine  which  appears  rolled  or 

convoluted. 

Ilium.    The  upper  portion  of  the  hip-bone  or  os  coxa. 
Incisor.     A  cutting  instrument.     The  front  teeth  are  incisors. 
Index.     Indicator.     The  first  finger  named  from  its  common  use. 
Induration.     Hardening  of  the  tissues. 
Infra.     Beneath. 

Infundibulurn.    A  funnel-shaped  space  or  part. 
Inhibition.     The  restraining  or  stopping  of  normal  action. 
Inguinal.     Belonging  to  or  near  to  the  thigh  or  inguen. 
Inlet.     The  superior  opening  or  brim  or  strait  of  the  pelvis. 
Innominatum'.    Unnamed. 
Inorganic.     A  term  applied  to  certain  substances,  mostly  mineral,"found  in  all  organs 

but  not  produced  by  them. 
Instep.     The  bend  of  the  foot,  dorsal  aspect. 

Inter.     Between,  as  intercostal,  between  ribs;  intercellular,  between  cells,  etc. 
Inversion.     A  turning  in,  as  inversion  of  the  eyelashes;  inversion  of  the  foot. 
Invertin.     The  ferment  of  intestinal  juice. 
Involution.     The  changing  back  to  a  former  condition,  of  an  organ  which  has  fulfilled 

a  function,  as  the  involution  of  the  uterus  after  parturition. 

Iris.     A  circle  or  halo  of  colors.     The  colored  circle  behind  the  cornea  of  the  eye. 
Ischium.    The  lowest  part  of  the  hip-bone  or  os  coxes. 

Jejunum.     Empty.    The  third  portion  of  the  small  intestine,  usually  found  empty. 
Jugular.     Belonging  to  the  neck  orjugulum. 
Kidney  or  ren  (plural,  renes).    An  important  organ  of  elimination  or  excretion,  in 

which  the  urine  is  formed. 
Labium.    A  lip.     (Plural,  labia). 

Lacrimal.     Having  to  do  with  tears  or  lacryma,  as  the  lacrimal  gland. 
Lacteal.    Like  milk  (from  lac,  milk).     The  lacteals  are  lymph- vessels  which  carry  the 

milky-looking  chyle. 
Lactose.    Milk  sugar. 

Lambdoid.     Resembling  the  Greek  letter  lambda,  X. 
Lamella.     A  little  plate,  or  thin  layer. 
Lamina.    A  plate  or  layer. 
Larynx.    The  part  of  the  air-passage  extending  from  the  base  of  the  tongue  to  the 

trachea. 

Latissimus.     Broadest.    Latissimus  dor  si,  broadest  of  the  back.  ^ 
Lens.    A  glass  or  crystal  curved  and  shaped  to  change  the  direction  of  (or  refract) 

rays  of  light. 

Lentiform.     Shaped  like  a  lens. 
Leptomeningitis.    Inflammation  of  the  thin  membranes  of  the  brain — the  arachnoid 

and  pia  mater. 

Lesion.     The  effect  of  an  injury,  or  of  disease,  in  a  tissue. 
Leucocyte.     A  white  cell  of  the  blood  or  lymph.    Leucocytosis,  an  increase  in  the 

number  of  leucocytes. 

Levator.     A  lifter.    Levatar  palpebrce,  lifter  of  the  eyelid. 
Linea.     A  line. 
Linea  alba.     A  white  line. 
Linea  aspera.    A  rough  line. 
Lingual.     Belonging  to  the  tongue  or  lingua. 
Lobule.    A  little  lobe. 
Lumbar.     Belonging  to  the  loin  or  lumbus. 
Macula.     A  spot.     Macula  lutea,  yellow  spot. 
Major.     Greater  or  larger. 
Malar.     Belonging  to  the  cheek  or  mala. 
Malleolus.    A  little  hammer.    The  two  malleoli  are  the  lower  extremities  of  tibia 

and  fibula. 

Mammary.     Pertaining  to  the  breast  or  mamma. 
Mandible.     Derived  from  mandere,  to  chew.     The  lower  jaw-bone. 
Manubrium.     A  handle.     The  first  part  of  the  sternum. 
Masseter.     A  chewer.     One  of  the  muscles  of  mastication  or  chewing. 


GLOSSARY  395 

Mastitis.     Inflammation  of  the  breast. 

Mastoid.     Shaped  like  a  breast. 

Maxilla.    The  jaw-bone.     Applied  to  the  upper  jaw-bone. 

Meatus.     A  passage. 

Medial.    Toward  the  middle  line. 

Median.     Middle,  as  the  median  line  of  the  body. 

Mediastinum.     From  Latin  words  meaning  to  stand  in  the  midst.     The  space  in  the 

middle  of  the  thorax. 
Medulla.     Marrow. 

Medullary.     Pertaining  to,  or  like,  marrow.     The  medullary  canals  contain  marrow. 
Meninges.     Membranes.     Membranes  of  the  brain  and  spinal  cord. 
Mental.     From  the  Latin  word  mens,  the  mind. 
Mental.     From  the  Latin  word  mentum,  the  chin. 
Mesentery.     From  two  Greek  words,  meaning  middle  and  bowel.     (The  mesentery 

connects  the  bowel  with  the  posterior  abdominal  wall.) 
Metastasis.     From  a  Greek  word  meaning  to  transpose. 
Minimus.    Least  or  smallest.     Minimi  digiti,  of  the  smallest  digit. 
Minor.     Lesser. 

Mitral.     Resembling  a  miter  in  outline. 

Molar.    Like  a  mill-storie  or  mola.     The  molar  teeth  grind  the  food. 
Mucous.     Containing  or  resembling  mucus. 

Mucus.     A  thick  clear  fluid  secreted  by  the  cells  of  mucous  membranes. 
Naris.     The  nostril.     (Plural,  nares.) 
Navicular.     Boat-shaped,  as  the  navicular  bone. 

Necrosis.     The  death  of  a  portion  of  tissue,  while  still  surrounded  by  living  structures. 
Neural.     Pertaining  to  nerves.     The  neural  axis  is  the  spinal  cord.     The  neural 

canal  is  the  spinal  canal.     The  neural  cavity  contains  the  brain  and  spinal  cord. 
Neuron.     A  single  nerve  cell  with  its  branches. 
Nucha.     The  nape  of  the  neck. 

Nucleolus.     A  smaller  nucleus  within  the  nucleus  of  a  cell. 
Nucleus.     A  small  round  body  near  the  center  of  a  cell.     The  most  important  part 

of  a  nucleated  cell. 
Neuron.     A  unit  of  the  nerve  tissues.     It  consists  of  cell  body  or  center,  axon  and 

terminal  divisions. 
Nutrient.     Nourishing. 

Nutrition.     The  process  of  nourishing  the  cells  of  living  tissues. 
Olecranon.     The  large  process  at  the  upper  end  of  the  ulna.     The  head  of  the  elbow. 
Occipital.     Belonging  to  the  back  of  the  head,  or  the  occiput. 
Odontoid.     Resembling  a  tooth  in  shape. 
Omentum.     A  fold  of  peritoneum  connected  with  the  stomach. 
Omos.     The  shoulder.     Omo-hyoid,  belonging  to  shoulder  and  hyoid  bone,  as  the 

omo-hyoid  muscle. 

Ophthalmic.     Belonging  to  the  eye  or  ophthalmos. 
Ora  serrata.     The  serrated  or  toothed  margin  of  the  retina. 
Orbicular.     Ring-shaped.     A  ligament  which  resembles  a  little  circle. 
Organ.     A  structure  designed  for  a  particular  function  or  use.     Organic  substances 

are  formed  in,  or  by,  organs. 

Os.     A  bone.     (Plural,  ossa.)     Ossicle,  a  little  bone. 
Os.     A  mouth.     (Plural,  ora.) 
Osseous.     Bony. 

Ossification.     The  formation  of  bone. 
Osteology.     The  science  which  treats  of  bones. 

Ostium  venosum.     A  venous  door.     The  door  or  opening  from  an  atrium  to  a  ven- 
tricle in  the  heart,  for  the  passage  of  venous  blood. 
Outlet.     The  inferior  opening  or  strait,  of  the  pelvis. 
Ovum.     An  egg.     (Plural,  ova.} 

Palpebra.     An  eyelid.    Palpebral  fissure,  the  Assure  between  the  eyelids. 
Pancreas.     From  words  meaning  all  and  flesh.     Pancreatic  fluid  digests  ail  foods. 
Papilla.     A  Latin  word  meaning  a  nipple.     A  soft  conic  eminence. 
Parietal.     Resembling  a  wall  (paries'). 

Parotid.     Near  the  ear.     The  parotid  gland  is  around  the  external  ear. 
Parturition.     The  act  of  bringing  forth,  or  giving  birth  to,  young. 
Patella.     A  little  pan.     The  sesamoid  bone  in  front  of  the  knee-joint;  the  "knee 

pan." 


396  GLOSSARY 

Pectoral.     Connected  with  the  breast,  as  pectoral  muscles. 
Pedicle.     A  little  foot.    Peduncle  has  a  similar  meaning. 
Pelvis.     A  basin.     The  cavity  in  the  lowest  part  of  the  trunk. 
Pericardium.     Around  the  heart. 
Perichondrium.     Around  cartilage. 

Perimysium.     The  connective  tissue  around  small  bundles  of  muscle  fibers. 
Perinea!.     Pertaining  to  the  perineum,  that  region  of  the  body  in  front  of  the  anus. 
Periosteum.     Around  bone. 

Peristalsis.     From  two  Greek  words,  meaning  around  and  constriction.     The  intes- 
tinal movements  which  propel  the  food. 
Peritoneum.     From  two  Greek  words,  meaning  around  and  to  stretch.     The  serous 

membrane  around  abdominal  organs. 
Peroneal.     Relating  to  the  fibula  or  perone.    Peroneal  nerves  supply  muscles  on  the 

fibula. 

Petrous.     Hard,  like  a  rock. 
Phagocyte.     White  blood-cells  having  the  power  to  take  micro-organisms  into  their 

substance  and  to  digest  them. 
Phalanges.     Plural  of  phalanx,  a  body  of  troops  drawn  up  closely  together.     The 

fingers  and  toes. 
Pharynx.     That  part  of  the  food  passage  which  connects  the  mouth  and  esophagus. 

The  upper  part  is  the  naso-pharynx,  an  air  passage. 

Phlebotomy.  Cutting  a  vein.  The  operation  of  bleeding  or  venesection. 
Phrenic.  Pertaining  to  the  phren  or  diaphragm,  as,  the  phrenic  nerves. 
Pia  mater.  Tender  mother.  The  delicate  membrane  which  bears  the  blood-vessels 

of  brain  and  cord. 
Pigment.     Coloring  matter. 

Plantar.     Belonging  to  the  sole  of  the  foot  or  planta. 
Plasma.     Something  moulded.     The  name  given  to  the  fluid  portion  of  the  blood, 

from  which  tissues  are  formed.     Lymph  plasma,  the  fluid  portion  of  lymph. 

Muscle  plasma,  the  fluid  portion  of  the  contents  of  a  muscle  cell. 
Platysma.     Broad.     Platysma  muscle. 
Pleura.     A  side.     The  name  of  the  serous  membrane  which  lines  the  thorax  and 

covers  the  lungs. 
Plexus.     A  network.     An  arrangement  of  vessels  and  nerves  which  appear  to  be 

woven  together. 

Pneumogastric.     Belonging  to  the  lungs  and  stomach. 
Pollicis.     Genitive  form  of  pollex,  the  thumb. 
Polymorphonuclear.     Having  nuclei  of  various  shapes. 
Poples.     The  ham;  a  space  behind  the  knee  (popliteal  space). 
Popliteal.     Belonging  to  the  poples  or  back  of  the  knee. 
Porta.     A  gate.     The  portal  vein  enters  the  porta  or  gate  of  the  liver. 
Prehension.     Taking  hold  of. 

Pre-molar.     Applied  to  the  teeth  which  stand  immediately  in  front  of  the  molars. 
Process.     In  anatomy,  a  projection. 
Pronation.    Literally,  bending  forward.     The  position  of  the  hand  when  the  thumb 

is  toward  the  body.     The  act  of  turning  the  hand  face  downward,  or  in  the 

prone  position. 
Prostate.     From  Greek  words  meaning  to  stand  before.     The  prostate  gland  is  in 

front  of  the  neck  of  the  bladder. 

Protoplasm.     A  simple  gelatinous  cell  substance.     Bioplasm. 
Protuberance.     A  knob-like  projection. 
Proximal.     Near  the  head  or  trunk. 
Psychic.     Pertaining  to  the  mind. 
Pterygoid.     Wing-shaped. 
Pubes.     The  anterior  portion  of  the  os  coxae. 
Pulmonary.     Pertaining  to  the  lung  or  pulmo. 
Quadriceps.     Four  headed. 
Rachitis.     From  two  words  meaning  spinal  column  and  inflammation.     A  disease  in 

which  the  bones  are  deficient  in  lime  salts. 
Radius.     A  rod  or  spoke.     The  lateral  bone  of  the  forearm. 
Ramus.     A  branch,  as  the  ramus  of  the  mandible. 
Raphe.     A  seam.     The  union  of  two  parts  in  a  line,  like  a  seam. 


GLOSSARY  397 

Reaction.     Response  to  a  stimulus  or  test.     The  iris  reacts  to  the  stimulus  of  light. 

Urine  reacts  to  the  litmus  test. 

Reflex  action.     The  simplest  form  of  nerve  response. 

Receptaculum  chyli.     Receptacle  of  the  chyle,  the  beginning  of  the  thoracic  duct. 
Recession.     Withdrawal,  as  the  margin  of  the  gums  from  the  teeth. 
Rectus.     Straight,  as  rectus  muscles.     Rectum  has  the  same  meaning. 
Recurrent.     Running  back.     Recurrent  arteries  turn  back. 
Renal.     Pertaining  to  the  ren  or  kidney. 
Retina.     A  net.     The  complicated  nerve  coat  of  the  eye. 

Rigor  mortis.     Rigidity  of  death.     The  muscular  stiffness  which  occurs  after  death. 
Rugae.     Folds.     (Plural  of  ruga.)     Wrinkles. 
Saccharose.     Cane  sugar. 
Sacral.     Relating  to  the  sacrum,  or  bone  which  protects  the  pelvic  organs  which 

were  held  sacred  by  the  ancients. 

Sagittal.     Like  an  arrow — straight.     The  straight  suture  of  the  skull. 
Saline.     Salty. 

Saliva.     The  mixed  secretions  of  glands  of  the  mouth  and  salivary  glands. 
Saphenous.     Manifest  or  plainly  seen.     The  large  superficial  vein  on  the  medial 

side  of  the  lower  extremity  and  the  longest  vein  in  the  body. 
Sartorius.     From  the  Latin  sartor,  tailor.     The  "tailor  muscle." 
Sciatic.     Ischiatic.     Pertaining  to  the  ischium. 

Sclerotic.     Hard.     The  sclerotic  is  the  tough  fibrous  coat  of  the  eye;  the  sclera. 
Scrobiculus  cordis.     Literally,  pit  of  the  heart.     The  little  depression  at  the  end  of 

the  sternum.     The  "pit  of  the  stomach." 

Sebaceous.  Applied  to  the  glands  which  produce  the  oil  or  sebum  of  the  skin. 
Secretion.  A  substance  either  nourishing  or  useful,  formed  by  glandular  cells. 
Septum.  A  partition.  (Plural,  septa.) 

Serous.     Of  the  nature  of  serum,  a  thin  watery  fluid  derived  from  the  blood. 
Serrated.     Having  teeth  like  the  border  of  a  saw.     (The  border  of  the  serratus  ant. 

muscle  is  thus.) 

Serum.     A  watery  fluid  separated  from  blood. 

Sesamoid.     Resembling  a  grain  in  form.     Applied  to  small  nodules  of  bone  some- 
times found  in  tendons. 
Shaft.     The  main  portion  of  a  long  bone. 
Sigmoid.     Curved  like  the  letter  S.     As  the  sigmoid  (or  transverse)  sinus;  the 

sigmoid  colon. 
Sinus.     A  curve,  or  a  hollow.     A  bone  sinus  contains  air.     An  abnormal  passage 

opening  on  the  surface  of  the  body  is  sometimes  called  a  sinus. 
Soluble.     That  which  can  be  dissolved  or  made  into  a  solution. 
Specific  gravity.     The  weight  of  a  substance,  judged  in  comparison  with  an  accepted 

standard.     In  the  case  of  urine,  the  standard  is  an  equal  volume  of  distilled 

water — at  greatest  density. 
Sphenoid.     Wedge-shaped. 
Sphincter.     A  muscle  which  closes  an  orifice. 
Splanchnic.     Pertaining  to  the  viscera  or  internal  organs. 
Squamous.     Shaped  like  a  scale. 
Steapsin.     The  pancreatic  ferment  which  digests  fats. 
Stereognosis.     The  faculty  of  recognition  of  objects  by  handling  them. 
Sternum.     Breast  bone. 

Stimulus.     That  which  excites  activity  or  function. 
Striated.     Striped. 

Styloid.  Pointed,  like  the  stylus,  which  was  used  in  ancient  times  for  writing. 
Sub.  Under. 

Subcutaneous.     Under  the  skin. 
Submucous.     Under  mucous  membrane. 
Subserous.     Under  serous  membrane. 
Sudoriferous.     Bearing  sweat,  as  sudoriferous  glands.     (Sudoriparous  has  the  same 

meaning.) 
Super.     Above. 

Superciliary.     Above  the  eyelashes. 

Supercilium.     The  eyebrow,  or  prominence  above  the  eyelashes. 
Supination.     The  attitude  of  one  lying  on  the  back.     The  position  of  the  hand  when 

the  little  finger  is  next  to  the  body,  or  when  lying  upon  the  back. 


398  GLOSSARY 

Supra.     Above. 

Sural.     Belonging  to  the  calf  or  sura,  as  the  sural  muscles. 

Surgical  neck.  The  constriction  below  the  head  of  a  long  bone  at  the  narrowest 
portion  of  the  shaft.  The  anatomic  neck  is  the  constriction  (however  slight) 
immediately  next  to  the  head,  between  it  and  the  shaft.  The  surgical  neck 
of  the  humerus  and  the  anatomic  neck  of  the  femur  are  best  examples. 

Suture.     A  seam.     (Latin,  sutura.)     The  joints  of  the  cranium  are  sutures. 

Symphysis.     A  growing  together,  as  the  symphysis  of  the  mandible. 

Synarthrosis.     An  immovable  joint. 

Synovia.  A  fluid  resembling  the  white  of  an  egg,  found  in  joint  cavities  and  vaginal 
synovial  membranes. 

Systole.  A  Greek  word  meaning  contraction.  The  contraction  of  the  chambers  of 
the  heart. 

Talus.     The  ankle  bone  upon  which  the  tibia  rests. 

Tendo  Achillis.  The  tendon  of  Achilles.  The  tendon  of  calf  muscles  attached  to 
the  calcaneus  or  heel  bone  by  which  Achilles  was  held  when  his  mother  sub- 
merged him  in  the  river  Styx,  to  render  him  invulnerable.  Only  the  heel 
remained  un-wetted. 

Tentorium.  A  tent.  The  tentorium  cerebelli  (of  the  cerebellum)  covers  the  cere- 
bellum. 

Teres.     Round.     (Ligamenlum  teres — round  ligament.) 

Testes,  or  Testicles.     The  glandular  bodies  which  secrete  semen. 

Thalamus.  A  Greek  word  meaning  a  bed.  The  optic  thalamus  is  in  the  base  or 
bed  of  the  brain. 

Thenar.  Relating  to  the  palm  or  sole.  Hypothenar — under  the  palm  or  sole — 
applied  tothe  eminences  on  the  side  corresponding  to  the  little  finger  or  toe. 

Thorax.     The  chest.     The  portion  of  the  trunk  which  contains  the  heart  and  lungs. 

Thyroid  or  thyreoid.     Shield  shaped. 

Torticollis.    Twisted  neck,  wry  neck. 

Trabeculae.  Little  beams.  (Plural  of  trabecula.}  The  cross  bands  of  connective 
tissue  which  support  soft  structures — as  in  the  spleen. 

Transudation.  The  passing  of  fluid  through  a  membrane,  as  of  the  blood  serum 
through  the  walls  of  vessels. 

Trapezium.  A  four-sided  symmetrical  figure.  Trapezoid,  resembling  a  trapezium, 
but  not  symmetrical.  Trapezius,  applied  to  a  muscle  of  the  back. 

Triceps.    Three  headed. 

Trigone.     A  space  or  surface  having  three  angles  or  corners. 

Trochanter.  From  a  word  signifying  a  wheel.  (The  muscles  which  are  attached 
to  the  trochanters  roll  the  femurs.) 

Trochlea.  A  pulley.  A  trochlear  surface  is  a  grooved  convexity,  as  the  trochlea  of 
the  humerus. 

Trypsin.    The  ferment  of  the  pancreas  which  digests  proteids. 

Tuber.    A  swelling  or  bump. 

Tubercle.    A  small  projection  like  a  swelling. 

Tuberosity.    A  large  projection  on  a  bone. 

Tumor.     A  swelling  of  soft  tissues. 

Turbinated.     Rolled,  like  a  scroll. 

Tympany.  The  condition  caused  by  inflation  of  intestines  with  gas,  so  that  they 
sound  hollow  upon  percussion,  like  a  tympanum  or  drum. 

Ulna.     A  cubit;  the  elbow.     The  longer  bone  in  the  medial  side  of  the  forearm.  ^ 

Umbilicus.  From  a  Latin  word,  umbo,  the  name  of  the  elevated  or  depressed  point 
in  the  middle  of  an  oval  shield. 

Ungual.     Belonging  to  the  nail  or  unguis. 

Urea.     A  substance  representing  the  chief  nitrogenous  product  of  tissue  waste. 

Ureter.     The  duct  of  the  kidney,  which  conveys  urine  to  the  bladder. 

Urethra.     The  passage  through  which  urine  is  expelled  from  the  bladder. 

Uvula.  From  uva,  a  grape,  or  cluster  of  grapes  (which  hangs  down  from  the  branch 
where  it  grows). 

Vaginal.    Like  a  sheath. 

Vagus.     From  vagare,  to  wander. 

Vallate.     Situated  in  a  cavity  which  is  surrounded  by  a  ridge. 

Valvulae  conniventes.  Little  valve-like  folds.  Seen  on  the  mucous  coat  of  the  small 
intestine. 


GLOSSARY  399 

Vascular.     Having  many  blood-vessels. 

Vaso -motor.  Literally,  vessel-mover.  Applied  to  the  nerves  which  dilate  blood- 
vessels or  contract  them,  or  vaso-dilators  and  vase-constrictors. 

Velum.  Veil.  Velum  palati,  the  veil,  or  soft  hanging  portion  of  the  palate  or  roof 
of  the  mouth. 

Vena  cava.     A  large  hollow  vein. 

Venesection.     Cutting  a  vein.     "Bleeding"  or  phlebotomy. 

Ventral.     Toward  the  front  of  the  body,  as  the  ventral  cavity. 

Ventricle.  Literally,  a  little  belly.  From  the  Latin  venter.  A  cavity  in  the  brain, 
or  in  the  heart. 

Vermiform.    Worm-shaped. 

Vertebra.  From  a  Latin  word  meaning  to  turn.  Certain  movements  of  the  verte- 
brae turn  the  body  from  side  to  side. 

Vertex.    The  crown  of  the  head. 

Vestibule.  A  cavity  of  the  internal  ear  through  which  stimulating  impulses  are 
transmitted  to  auditory  and  vestibular  nerves. 

Villus.  A  hair  (pi.  villi).  The  villi  of  the  intestine  are  hair-like  in  shape  and  belong 
to  the  mucous  coat. 

Viscus.     An  internal  organ  of  the  head  or  trunk.     (Plural,  viscera.) 

Vitreous.  Glassy.  The  vitreous  humor  resembles  glass  in  appearance.  The 
vitreous  layers  of  the  skull  are  brittle  like  glass. 

Volar.     Belonging  to  the  palm  or  vola. 

Xyphoid.  Sword-shaped.  The  third  piece  of  the  sternum  is  the  xyphoid  or  ensiform 
appendix. 

Zygoma.  A  yoke.  The  arch  of  bone  at  the  side  of  the  face  formed  by  zygomatic 
processes  of  frontal  and  maxillary  bones. 


INDEX 


Abdomen,  abdominal  organs,  365,  367 

regions  of,  366 

Abdominal  brain  (Solar  Plexus),  318 
Abdominal  wall,  94 
Absorption,  166,  169 
Accommodation,  338 
Acetabulum,  48 
Acromegaly,  267 
Adipose  tissue,  4,  5 
Adrenal  bodies,  264 
Air  or  atmosphere,  23 1 

air  cells,  236 

tidal  volume,  239 
Alimentary  canal,  130 
Ameboid  movements,  173 
Anatomic  position  and  use  of  terms,  i 
Animal  heat,  274 
Antrum  of  Highmore,  25 
Aorta,  187,  189 
Apnea,  242 
Aponeurosis,  description  of,  84 

vertebral,  86 
Apophysis,  15 

Appendix  ceci  (vermiformis),  144 
Aqueduct    of    Sylvius    (of     cerebrum), 

303 

Aqueous  humor,  338 
Arachnoid  of  brain,  305 

of  cord,  281 

Arbor  vitae,  302  (illus.  301) 
Arches  of  foot,  73 

of  hand,  192,  193 

of  vertebrae,  39 

palatine,  133 

superciliary,  21 

supraorbital,  20 

zygomatic,  33 
Areolar  tissue,  5 
Arm,  bone  of,  56 

muscles  of,  104 

Arterioles  and  arteries,  174,  175 
Arterio-sclerosis,  216 

26  401 


Articular  surface,  13 
Articulations  or  joints,  17 

of  cranium,  24 

of  face,  28 

of  lower  extremity,    70 

of  pelvis,  49,  50 

of  spinal  column,  42 

of  thorax,  47 

of  upper  extremity,  60 
Ascites,  7 
Asphyxia,  241 
Assimilation,  166 
Associated  movements,  344 
Atlas,  40 

Auditory  tube  (Eustachian),  330 
Auricle  of  heart,  176 
Axillary  space,  368 
Axis  (artery),  191 

(bone),  40 
Axon,  278 

Bifurcation  of  aorta,  198 
Bile,  150 
Bioplasm,  4 
Bladder,  urinary,  246 
Blood,  171 

circulatory  organs  of,  174 

coagulation  of,  217 

pressure,  216 
Bone,  articular,  13 

markings,  13 

nutrition,  15 

repair  of,  77 

tissue,  ii 
Bones,  completion  of,  76 

in  infancy,  75 

shapes  of,  14 

structure  of,  1 1 
Brain,  299 

fissures  of,  300 
Brain  hemispheres,  300 

lobes  of,  300 


402 


INDEX 


Breast  (mammary  gland),  260 

muscles  of,  103 
Bronchi,  234 
Bronchial  muscle,  235 
Bursa  (plural,  burses},  71,  82 

prepatellar,  72 

Callus,  78 

Canal,  adductor,  371 

anal,  146 

auditory,  329 

carotid,  23 

central  (of  cord),  303 

femoral,  371 

Haversian,  12 

Hunter's  (or  adductor),  371 

inguinal,  371 

internal  auditory,  23 

medullary,  14 

nasal  (or  lacrimal),  34 

neural,  53 

nutrient,  15 

semicircular,  331,  332 

spinal  (neural  or  dorsal),  43,  53 
Cancellous  or  spongy  tissue,  12 
Capillaries,  175 
Capitulum  (capitellum),  56 
Capsule,  Bowman's,  246 

internal,  of  brain,  301 

of  joints,  1 8 

of  lens,  337 

of  Tenon,  335 
Carbohydrates,  153 
Cardiac  impulse,  177 
Carpus,  58 

meta,  59 
Cartilage,  5 

articular,  17 

costal,  44 

fibro-,  semilunar,  70 
sterno-clavic.,  60 
triangular,  62 
Cartilages  of  larynx,  233 
Cauda  equina,  284 
Cavities  of  body,  53 

dorsal  or  neural,  53 

ventral  or  visceral,  53 
Cecum,  144 
Cell  body  (nerve),  277 
Cell,  description,  4 


Centers,  brain  (illus.),  311,  314 

nerve,  279 

of  ossification,  15 
Central  fissure,  301 
Cerebellum,  302 
Cerebral  localization,  311 
Cerebro-spinal  fluid,  280 

system,  279 

Cerebrum,  300,  322,  324 
Cervical  nerves,  286 
Cervix  uteri,  347 
Chambers  of  eye,  338 
Cheyne-Stokes  breathing,  242 
Choroid  coat  of  eye,  336 
Chyle,  161,  168,  222 
Chyme,  160 
Cilia,  of  air  passages,  233,  235 

of  eyelids,  343 
Ciliary  muscle,  338 
Circular  folds  (intestine)  142 
Circulation  (def.),  166 

collateral,  195,  200,  380-385 

fetal,  209,  211,  356 

portal,  208,  209 

pulmonary,  185,  187 

systemic,  185,  187,  188 
Circumcision,  354 
Clitoris,  351 

Coagulation  of  blood,  217 
Coccyx,  42 
Cochlea,  331,  333 
Colon,  145 
Colostrum,  262 
Compact  bone  tissue,  1 2 
Compression  of  arteries,  378 
Condyle  (def.),  13 
Condyles,  occipital,  21 

of  femur,  66 

of  mandible,  27 

of  tibia,  66 
Conjoined  tendon,  96 
Conjunctiva,  336-341 
Connective  tissue,  5 
Coordination,  297,  322 
Corium   of   skin    (cutis   vera), 

253 

Cornea,  335 

Corpus  callosum,  300,  301  (Illust.) 
Corpuscle  of  blood,  171,  172,  173 
of  kidney  (Malpighian),  245 


INDEX 


403 


Corpuscle  of  skin  (touch),  254,  327 

of  spleen,  263 
Corpus  luteum,  349-350 
Cortex  of  adrenal  body,  264 

of  brain,  299 

of  kidney,  245 
Cranium,  20,  29 
Crest  (def.),  13 

of  ilium,  48 
Crura  of  cerebrum,  303 

of  diaphragm,  98 
Crystalline  lens,  337 
Cutis  vera  (skin),  253 

Dartos,  353 

Decidual  membrane,  355 

Defecation,  165 

Deglutition,  158 

Dendrite,  277 

Dentition  (eruption  of  teeth),  36 

Diameters  of  pelvis,  52 

Diapedesis,  173 

Diaphragm,  97,  121 

of  pelvis,  no 
Diaphysis,  15 
Diastole  of  heart,  180 
Digestion,  156 
Digestive  fluids,  131 
Duct,  common  bile,  150 

cystic,  150 

hepatic,  149,  150 

pancreatic,  148 

right  lymphatic,  223,  228 

Stenson's,  134 

thoracic,  223,  228 

Wharton's,  134 
Ductus  arteriosus,  210 

communis  choledochus  (or  common 
bile  duct),  150 

deferens  (vas  def.),  354 
Duodenum,  141,  142 
Dura  mater,  brain,  305 

cord,  281 
Dyspnea,  242 

Ear,  329 
Edema,  229 
Elastic  tissue,  5 
Elimination,  organs  of,  244 


Endocardium,  178 
Endosteum,  14 
Endothelium,  7 
Enzymes  (def.),  131,  165 
Epicardium,  183 
Epicondyle  of  femur,  66 

of  humerus,  56 
Epidermis,  254 
Epiglottis,  233 
Epiphysis,  15 
Epithelium,  6,  7 

ciliated,  6,  233 

respiratory,  230,  233 
Erythrocyte  (red  cell),  171 
Esophagus,  135,  136 
Eustachian  tube  (auditory),  330 
Excretion,    270 
Expiration,  act  of,  238 
External  genital  organs,  351 
Extremities  compared,  372 
Eye,  335 
Eyebrows,  341 
Eyelids,  341 

Face,  bones  of,  24 

muscles  of,  89,  90,  91 

vessels  and  nerves,  360 
Fallopian  or  uterine  tubes,  348 
Falx  cerebri,  305 
Fascia  of  body,  deep,  80 

iliac,  in 

lata,  8 1 

lumbar,  82 

palmar,  109 

pelvic,  in 

plantar,  118 

superficial,  82 

temporal,  90 

transversalis,  100,  in 

transverse  of  leg,  377 
Fatigue  poisons,  126 
Fats,  153,  154 
Feces,  164 
Fibrin,  218 
Fibrous  tissue,  5 
Fissure  of  Rolando  (central),  300 

of  Sylvius,  301 

transverse  of  liver  (porta),  148 
Floor  of  mouth,  131 


404 


INDEX 


Floor  of  pelvis,  no 

of  thorax,  98 
Fontanelles,  32 
Food,  absorption  of,  166 

values,  272 
Foods,  153 

carbohydrates,  fats,  proteids,  153, 

154,  i55 
Foot,  eversion  of,  119 

inversion  of,  119 
Foramen,  infraorbital,  31 

intervertebral,  44 

jugular,  31 

magnum,  21 

mental,  31 

Munro,  303 

obturator  or  thyroid,  49 

optic,  34 

ovale,  210 

sciatic,  50 

supraorbital,  21 

transverse,  40 

vertebral,  39 
Forearm,  bones  of,  57 

muscles  of,  105 
Foreskin  (prepuce),  354 
Fossa  (def.),  13 

glenoid,  55 

intercondyloid,  66 

ischio-rectal,  368 

lacrimal,  21 

mandibular,  22 

navicularis,  351 

ovale  (heart),  177 
(thigh),  82 

subscapular,  55 
Fossae  of  skull,  32 
Frenum  linguae  (bridle  of  tongue),  132 

Gall  bladder,  150 
Ganglia,  basal,  301 

-semilunar,  318 

sympathetic  (autonomic),  316 
Ganglion,  279 

Gasserian,  307 

root  of  spinal  nerve,  282 
Gastric  juice,  139 
Glabella,  21 

Gladiolus  (body  of  sternum),  44 
Glands  of  Bartholin,  352 


Glands,  ceruminous,  256,  329 

digestive,  131 

ductless,  262 

Peyer's  (or  patches),  144 

lacrimal,  343 

lymph,  223 

mammary,  260 

Meibomian  (tarsal),  342 

prostate,  346 

salivary,  134 

sebaceous,  255 

structure  of,  8 

sudoriferous,  256 

tissue,   7 
Glottis,  345 
Graafian  follicle,  349 
Greenstick  fracture,  56,  77 
Glycogen,  168 

Hair,  257 

Hamstring  tendons,  114,  115 

Hearing,  329 

Heart,  176 

cycle  of,  1 80 

diastole  of,  178 

function  of  chambers,  180 

muscle,  176 

nerves  of,  185 

sounds,  182 

systole  of,  180 

tendinous  cords  of,  1 78 

valves  of,  179 
Hematin,  172 
Hemoglobin,  172 
Hemorrhage,  217 

control  of,  219 

Hemorrhoidal  arteries,  198,  199,  200 
Hernia,  372 

retro-peritoneal,  368 
Hilus  or  hilum,  2 

of  kidney,  244 

of  lung,  236 

of  spleen,  151 
Hip-bone  (os  coxae),  48 
Housemaid's  knee,  82 
Hydrocephalus,  303 
Hymen,  352 
Hyperemia,  229 
Hyperpnea,  242 
Hypodermoclysis,  214 


INDEX 


405 


Hypophysis  cerebri,  267 
Hypothear  muscles,  109 

Ileum,  142,  143 
Ilium  (os),  48 
Inflammation,  229 
Inguinal  rings,  371 
Inorganic  substances  of  bone,  n 
Insertion  of  muscles,  85 
Inspiration,  act  of,  238 
Instep  (arches  of  foot),  73 
Intercellular  substance,  4 
Intermuscular  septa,  81 
Interosseous  spaces,  57,  66 
Intestine,  139 

large,  144 

small,  141 
Iris,  336 
Isthmus  of  fauces,  133 

Joint  or  articulation,  17 
immovable,  17 
motions  of,  18 
movable,  17 
yielding,  18 

Kidney,  floating,  252 
Kidneys,  244 

Labia  majora,  351 

minora,  351 

Labyrinth  (ear),  331,  332 
Lacteals,  168,  227 
Lanugo,  257 

Large  vessels  and  nerves  (location),  377 
Larynx,  233 
Leucocytes,  172,  173 
Leukemia,  152 
Ligament,  annular,  109,  119 

of  Bigelow  (Y)  ileo-femoral,  69 

broad,  350 

crucial,  71 

deltoid,  72 

elastic,  42,  73 

Gimbernat's,  372 

inguinal  (Poupart),  50,  81,  96 

of  liver,  150 

orbicular,  64 

of  patella,  70,  112 

sacro-sciatic,  50 


Ligament,  suspensory  of  lens,  337 

transverse  of  ankle,  72 
Ligaments  of  uterus,  350 
Ligamentum  nuchae,  43 

teres,  69,  70 
Linea  alba,  96 

aspera,  66 

semilunaris,  95 
Lineae  trans versae,  97 
Liver,  148 
Lochia,  358 

Lumbo-sacral  cord,  291 
Lungs,  235 
Lymph,  170,  223 

capillaries,  221 

corpuscles,  223 

nodes  (lymphatic  glands),  223 

origin  of,  222 

spaces,  221 

vessels,  221 
Lymphatic  ducts,  223 
Lymphocytes,  223 
Lymphoid  tissues,  9,  223 

Malleolus,  lateral,  65 

medial,  65 
Manubrium,  44 
Marrow,  12 
Mastication,  157 
Meatus,  external  auditory,  329 

of  nose,  33,  233 

of  urethra,  247,  351 
Median  line,  2 
Mediastinum,  365 
Medulla  (of  brain),  302,  322 
Medullary  canal,  14 
Medullated  fibers,  277 
Membranes,  7 

of  brain,  305 

mucous,  serous,  synovial,  7 

of  spinal  cord,  281 
Menopause  (climacteric),  349 
Menstruation,  349 
Mesentery,  147 
Metabolism,  8,  270 
Metastasis,  229 
Micturition,  249 
Milk,  261 
Mons  veneris,  351 


406 


INDEX 


Motions  of  eyeball,  343 
Moulding  of  head,  32 
Mouth  (oral  cavity),  131 

breathing,  239 

Movable  joint,  description  of,  17 
Muscle  band  of  His,  177 

cell,  83,  122 

tissue,  83,  119 
Muscles,  action  of,  126 

modifications,  125 

of  abdomen,  94-97 

of  back,  85 

of  breast,  103 

of  face  (or  of  expression),  89-91 

of  head  and  neck,  86,  93 

of  lower  extremity,  109 

of  mastication,  90 

of  pelvis,  109,  no,  in 

of  upper  extremity,  101 

ribbon,  92 

stimulus  of,  122 

structure  of,  83, 

tension  of,  120,  122 
Myocardium,  176 

Nails,  256 
Nares,  34,  233 
Nasal  breathing,  239 
Nasopharynx,  135 
Necrosis  (of  bone),  13 
Nerve  centers,  279 

cylinder,  278 

plexus,  285 

supply  to  joints,  74 
to  muscle  groups,  128 

tissue,  277 
Nerves,  cervical,.  286 

coccygeal,  294 

cochlear,  333 

cranial,  305 

femoral,  292 

lumbar,  291 

motor,  279,  321 

optic,  337 

phrenic,  286 

pneumogastric,  309 

sacral,  292 

sciatic,  292 

sensory,  281, 


Nerves,  spinal,  284 

thoracic,  291 
Neurilemma,  278 
Neuron,  277 
Nose,  231 
Notch,  ethmoid,  21 

intercondyloid,  65 

radial,  57 

sciatic,  49 

sternal  or  jugular,  44 

supraorbital,  21 

Notes  clinical,  blood-vessels,  214,  216, 
219 

bones,  28,  34,  37,  38,  43,  56 

digestive    organs,    133,    139,     144 
146,  151,  152 

kidney,  248,  249,  250,  251 

lymph  system,  228,  229,  230 

muscles,  88,  125 

nerve  system,   282,  303,  305,  309, 

3i3 

pelvic  organs,  350,  357 

regional,  363 

respiratory,  237 

skin,  255,  256,  258,  259 

special  senses,  326,  331,  338,  343 

spleen,  152 

Notes  obstetric,  32,  50 
Notes  practical  and  special,  blood-ves- 
sels, 172,  175,  185,  193,  195,  197, 

200,   212 

bones,  57,  58,  66,  71,  73,  76,  78 

muscles,  81,  90,  98,  103,  112,  121 

regional,  361 
Notes  surgical,  abscess,  100,  262 

blood-vessels,  175,  193 

bones,  28,  63,  72,  75,  78 

digestive  organs,  146 

kidney,  248 

muscles,  82,  117,  131,  262 

nerves,  282,  304,  305,  308 

regional,  363,  368 
Nucleus  and  nucleolus,  4 

caudate,  301 

lentiform,  301 
Nutrient  artery,  15 

Obturator  membrane,  49 
Olfactory  region,  326 


INDEX 


407 


Omentum,  148 

Opsonic  index,  220 

Optic  commissure  (chiasm),  307 

disc,  337 

thalamus,  301 
Orbit,  33 

Organ  and  organic  substance,  7, 
Origin  of  blood  cells,  172,  173 

of  muscles,  85 
Os  coxae  or  hip  bone,  48 
Osmosis,  170,  214,  229 
Osseous  tissue,  5,  n 
Ossicles,  332,  333 
Ossification,  14 
Ovary  and  ovum,  348,  349 
Ovulation,  349 

Palate,  hard,  26,  131 

soft,  131 

Palm,  or  metacarpus,  59 
Pancreas,  148,  263 
Papilla  of  hair,  257 

of  skin,  254 

tongue,  132 
Parathyroids,  266 
Patella,  68 

Peduncles  of  brain,  303 
Pelvic  floor,  no 

girdle,  51 

organs,  346 
Pelvis,  51 
Pepsin,  139 
Peptones,  159,  160 
Pericardium,  183 
Perichondrium,  5 
Perineal  arteries,  200 
Perineum,  353 
Perineurium,  279 
Periosteum,  13 
Peristalsis,  147 
Peritoneum,  367 
Peri  vascular  spaces,  221 
Perspiration,  258 
Peyer's  patches,  144 
Phagocytes,  173,  214,  230 
Phagocytosis,  173 
Phalanges,  59 
Pharynx,  134,  233 
Physiology  of  blood,  213 


Physiology  of  bone,  78 

of  brain,  311 

of  cord,  295 

of  digestive  organs,  153 

of  kidneys,  248 

of  lymph  system,  228,  230 

of  muscle,  119 

of  nerve  system,  321 

of  ovary,  349 

of  respiratory  organs,  237 

of  skin,  257 

of  sympathetic  nerves,  318,  321 

of  uterus,  348,  357,  358 
Pia  mater  of  brain,  305 

of  cord,  281 
Pillars  of  fauces,  133 
Pituitary  body  (hypophysis),  267 
Placenta,  212,  357 

previa,  359 
Plasma,  171,  173 
Pleura,  236 
Plexus,  285 

brachial,  287 

cardiac,  318 

celiac,  318 

cervical,  286 

hypogastric,  318 

lumbar,  291 

pulmonary,  318 

sacral,  292 
Pons  varolii,  303 
Popliteal  plane,  66 

space,  114,  371 
Porta  of  liver,  148 
Portal  vein,  209 
Pouch  of  Douglas,  353 
Pregnancy,  357 
Process  (def.)  13 

acromion,  55 

alveolar,  26,  27 

articular,  39 

coracoid,  55 

coronoid,  57 

frontal,  26 

mastoid,  22 

odontoid,  40 

olecranon,  57 

palate,  26 

pterygoid,  24 


408 


INDEX 


Process,  spinous,  39 

styloid,  23 
of  fibula,  66 
of  radius,  57 
of  ulna,  57 

transverse,  39 

unciform,  58 

zygomatic,  26 
Promontory,  42 
Pronation,  64 
Proteids,  153,  154 
Protoplasm,  4 
Ptyalin,  134,  158 
Puberty,  349 
Pubic  arch,  49 

symphysis,  49 
Pudendum,  351 
Pulse,  181 
Pylorus,  138 
Pyramids  and  tracts  (medulla),  302 

decussation  of,  302 

Rachitis,  77 

Receptaculum  chyli,  223 
Reciprocal  reception,  63 
Rectum,  146 
Reference  tables,  379 
Reflex,  abdominal,  297 

action,  296 

patellar,  297 

plantar,  297 

skin,  297 

tendon,  297 
Rennin,  139 
Respiration,  231 

artificial,  242 

external,  231 

influence  of  drugs,  241 

internal,  231 

modifications  of,  242 

rate  of,  238,  239 

stimuli,  240,  241 

variations,  240,  241, 
Respiratory  sounds,  239 
Retina,  337 
Ribs,  44 
Rigor  mortis,  124 

Sacrum,  41 
Saddle  joint,  19,  63 


Saliva,  134 

Sartorius  or  "tailor  muscle,"  112 

Scalp,  360 

Scarpa's  triangle,  370 

Schneiderian  membrane,  233,  326 

Sclera,  335 

Scorbiculus  cordis,  366 

Scrotum,  353 

Secreting  organs,  7,  269 

Secretions,  7,  269 

internal,  263,  269 
Semilunar  notch,  57 
Septum,  34 

intermuscular,  81 
nasal,  34,  232 
Serum,  217.  218 
Sheath  of  rectus,  97 
Shoulder  girdle,  56 
Sigmoid  groove,  22,  305 
Sight,  335 
Sinus  (def.),  2 
ethmoid,  23 
frontal,  21 
of  kidney,  245 
maxillary,  25 
sagittal,  22 
sphenoid,  24 

transverse  (lateral),  22,  204 
Sinusitis,  35 
Skeleton,  15 

at  different  ages,  75 
Skin,  253 

Skull,  as  a  whole,  29 
at  birth,  32 
completion  of,  75 
points  of  interest,  29 
Smell,  326 
Special  senses,  325 
Speech,  312,  345 
Spermatic  cord,  354 
Sphincter,  anal,  146 
cardiac,  138 
ileo-colic,  143 
pyloric,  138 
vesical,  247 
Spina  bifida,  77 
Spinal  canal,  42,  43 
column,  43 
cord,  280,  321,  322 


INDEX 


409 


Spinal  curves,  44 
Spine  (def.),  13 

intercondyloid,  65 

of  ilium,  48 

of  ischium,  49 

of  pubes,  49 

of  scapula,  55 

of  tibia,  65 

Splanchnic  nerves,  318 
Spleen,  lien,  151,  264 
Spongy  or  cancellous  tissue,  12 
Sternum,  44 
Stomach  (gaster),  137 

of  infant,  139 
Straits  of  pelvis,  51 
Summary,  cerebro-spinal  nerves,  310 

functions  of  cranial  nerves,  314 

nerve  system,  321 

return  of  lymph,  228 

return  of  venous  blood,  207,  208 

spinal  nerves,  295 
Supination,  64 
Sutures,  24 

Sympathetic  (autonomic)  nerves,  316 
Symphysis  pubis,  49,  50 
System  (def.),  8 

Tactile  cells,  327 
Tables  of  skull,  29 
Tarsus,  67 

meta,  68 
Taste,  133,  328 
Teeth,  35 

eruption  of,  dentition,  36 
Temperature  of  body,  274,  275 
Tendinous  cords,  198 
Tendon  of  Achilles  or  tendo  calcaneus, 

68,  118 

Tendons,  84,  85 
Tentorium  cerebelli,  305 
Terminal  filament,  280 
Testes,  353 

Thenar  eminences,  109 
Thorax,  363 
Thrombin,  218 
Thymus  body,  266 
Thyroid  (thyreoid)  body,  265 
Tissues,  4 

contractile,  83 


Tissues,  fluid,  9 
Tissue  spaces,  80 
Tongue,  131,  132 
Tonsil,  133 

lingual,  133 

palatine,  133 

pharyngeal,  135 
Touch,  327 
Trachea,  234 
Triangles  of  neck,  362 
Trigone,  bladder,  247 

femoral,  200,  370 
Trochanters,  66 
Trochlea,  56 
Trophic  centers,  297 
Trunk,  17,  44 

Tuber  ischii  (tuberosity),  49 
Tuberosity  of  calcaneus,  67 
Tympanum,  330 

Umbilical  artery,  201 

cord,  212 

vein,  210 
Umbilicus,  96 
Urea,  249 
Ureter,  247 
Urethra,  247 
Urethral  caruncle,  248 
Urination  (micturition),  249 
Urine,  249 

Uterine  tubes  (Fallopian),  348 
Uterus,  346 
Uvula,  131 

Vagina,  350 

Vaginal  sy  no  vial  membranes,  107 

Valve,  Eustachian,  of  heart,  210 

Houston's,  146 

ileo-cecal,  145 
Valves  of  heart,  179 

of  veins,  175 
Vasa  vasorum,  176 
Vaso  motor  nerves,  320 
Vein,  jugular,  204 

portal,  209 

umbilical,  209,  210 
Veins,  203 

azygos,  206 

structure,  175 


410  INDEX 

Velum  palati,  131  Vitreous  layer  (cranial  bones),  29 

Vena  cava  inferior,  208  Viscera,  abdominal,  367 

superior,  206  thoracic,  365 

Ventilation,  243  "Vital  knot"  (nceud  vital),  314 

Ventricles  of  brain,  303  Vocal  bands  and  voice,  345 

of  heart,  177  Vola,  palm,  74. 
Vermis  (of  cerebellum),  302 

Vertebrae,  39,  40,  41  Wharton's  jelly,  212 
Vertebral  aponeurosis,  86 

Vertex  of  skull,  29  Xyphoid  appendix,  44 
Vestibule  (ear),  331 

(pudendum),  351  Y-ligament,  70 
Villi,  141,  142 

Vitreous  body,  337  Zygoma  (process),  22 


31199 
tomy  and 


